Chapter 15 – Analyzing the Incident

Part 1 – Chapter Objectives, Introduction, Analytical Methods, and Timelines

Knowledge Objectives

After studying this chapter, you should be able to:

• Identify analytical tools used in fire investigation. (NFPA 1033: 4.6.2; 4.6.5, pp. 360–368)

• Explain the use of timelines in fire investigation. (NFPA 1033: 4.4.3; 4.6.2, pp. 360–362)

• Explain the purpose and implementation of system analysis in fire investigation. (NFPA 1033: 4.4.3; 4.6.2, pp. 362–364)

• Identify the components of mathematical and engineering modeling, and explain how they can be used to investigate fire incidents. (NFPA 1033: 4.4.3; 4.6.2, pp. 364–365)

• Explain the use of graphic representations, including computer modeling, in fire investigation. (NFPA 1033: 4.4.3; 4.6.2, pp. 364–365)

• Explain the process of fire testing and its importance in fire investigation. (NFPA 1033: 4.4.3; 4.6.2, p. 368)

• Identify and describe incendiary fire indicators. (NFPA 1033: 4.2.3; 4.2.6, pp. 370–380)

• Describe the assessment of fire growth and damage in incendiary fires. (NFPA 1033: 4.2.3; 4.2.6, pp. 374–375)

• Identify and describe potential incendiary fire indicators not directly related to combustion. (NFPA 1033: 4.2.3, pp. 375–377)

• Describe factors to consider after a determination is made that a fire was incendiary. (NFPA 1033: 4.6.4, pp. 378–380)

• Recognize the motive(s) for a fire based on the known list of motives for fire-setters. (NFPA 1033: 4.6.4, pp. 378–380)

• Describe the general characteristics of human response at a fire incident. (NFPA 1033: 4.6.4, pp. 380–381)

• Describe how specific features of a fire and fire environment can impact human behavior. (NFPA 1033: 4.6.4, pp. 380–381)

• List ways that human action or inaction can impact fire occurrences. (NFPA 1033: 4.6.4, pp. 382–385)

• Describe the three recognized age categories of youth fire-setters, and summarize the reasons that youths are drawn to setting fires. (NFPA 1033: 4.6.4, pp. 384–385)

• Describe the ways in which an occupant may react once a fire threat is identified. (NFPA 1033: 4.6.4, p. 385)

Skill Objectives

After studying this chapter, you should be able to:

• Reference standards, guidelines, and regulations dealing with safety warnings and product design.

• Use analytical tools as part of a fire investigation. (NFPA 1033: 4.6.5, pp. 360–368)

• Use models to analyze fire incident data. (NFPA 1033: 4.4.3; 4.6.2, pp. 364–365)

• Examine fuel loads and their composition and location to understand fire growth.

• Recognize the various motives of fire-setters. (NFPA 1033: 4.6.4, pp. 378–380)

• Examine fire protection systems to determine whether they have been altered or sabotaged. (NFPA 1033: 4.6.4, pp. 375–378)

• Analyze fire-related human behavior. (NFPA 1033: 4.6.4, pp. 382–385)

• Integrate knowledge of human behavior into the total fire investigation. (NFPA 1033: 4.6.4, pp. 382–385)

• Gather evidence of motive and opportunity related to an incendiary fire. (NFPA 1033: 4.6.4, pp. 378–380)

Introduction

The scientific method is the overall methodology used to determine a fire’s origin and cause. As part of that method, a fire investigator can use several techniques to analyze:

• The fire’s cause

• Its development

• Other factors that may have contributed to its spread or severity

The following topics describe techniques investigators use during the analytical phase of a fire incident investigation.

Analytical Methods

Investigators will often encounter a multitude of facts and data during a fire or explosion investigation. To formulate hypotheses, they must be able to organize and analyze this information.

Analytical tools that can assist in interpreting the information obtained include:

• Timelines

• System analysis

• Mathematical/engineering modeling

• Graphic representations

• Scene reconstruction

• Fire testing

Timelines

A timeline is a graphic or narrative representation of events related to a fire incident, arranged chronologically.

Understanding an incident’s timeline is fundamental to performing failure analysis because it helps determine the sequence of events. A timeline is a comprehensive listing of specific, relevant events that can be verified to a stated degree.

Timelines may include events occurring:

• Before the fire

• During the fire

• After the fire

Estimates of fire size or conditions are often valuable when developing timelines. By applying known information about fire dynamics, fire conditions can be related to specific events. Information gathered from fire-detection and suppression systems may also help determine fire spread and establish when specific events occurred.

A timeline’s value is directly related to the accuracy of the information it contains, while its reliability depends on the level of confidence that can be placed in its individual elements. Not every item can be traced to one specific time; some events may have to be listed as occurring within a time interval.

Timeline components include incidents described as either:

• Hard times

• Soft times

Hard Times

Incidents that can be related to a known exact time are generally called hard times. The occurrence time is specifically known.

For example, a fire department’s incident-history records can provide exact times for unit dispatch, arrival on scene, and other operational benchmarks. These data serve as benchmarks when developing the timeline.

Table 15-1 – Hard Time Sources

When collecting hard-time information, the investigator must verify whether the time recorded by the source or source device is accurate.

For example, if a surveillance camera’s clock was incorrect when the investigator obtained its recordings, the displayed time will also be inaccurate. The investigator may be able to use the current discrepancy to determine the actual recording time. If the camera shows 4:30 p.m. when the actual time is 3:30 p.m., an activity time-stamped 10:00 a.m. actually occurred at 9:00 a.m.

Soft Times

Other times can be considered soft times. A soft time is estimated or relative and is generally supplied by witnesses.

A witness may be unable to state exactly when an event occurred, such as:

• When flashover occurred

• When an occupant was told to leave a building

However, the witness may be able to relate the observation to another event, including:

• The fire department’s arrival

• The moment a bus or train went by

• When a television program was on

• Another identifiable event

Through interviews and further data gathering, the investigator may be able to narrow the time range for these soft-time events.

Relative Time

Relative time can be subjective and varies with the witness providing the information. When giving information, witnesses should relate actions and observations to one another and to events that occurred before them. The account should be as specific as possible.

Estimated Time

Estimated time is an approximation based on information or calculations that may or may not be relative to other events or activities.

Benchmark Events

Some events are especially valuable as the foundation for a timeline or may have a significant relationship to a fire’s cause, spread, detection, or extinguishment. These are called benchmark events.

For example:

1. Mr. Jones ends his workday and punches out at 6:00 p.m.

2. He begins his 25-mile drive home through heavy traffic.

3. As he turns onto a side street, he passes a furniture store that appears closed and quiet.

4. He continues traveling and passes the fire station, where he sees fire trucks responding to a fire at the furniture store.

5. The trucks radioed their departure at 6:32 p.m.

Using Mr. Jones’s work time-clock record and the fire department’s dispatch records as benchmark events, the investigator may be able to establish an estimated relative time for when Mr. Jones passed the store.

Multiple Timelines

A variety of timelines may be required to evaluate and document effectively:

• The sequence of events that precipitated the fire

• Events during the actual fire incident

• Postfire activities

Depending on the incident’s complexity, events may be evaluated using a macro timeline or a micro timeline.

Macro Timeline

A macro evaluation can cover months or years and may incorporate activities that occurred long before the fire, such as those associated with:

• Building construction

• Modification of codes

• Code-enforcement activities

Micro Timeline

A micro evaluation examines a small or narrow portion of the macro timeline in detail. Examples of micro incidents could include:

• The time required for a witness to walk between rooms

• The time between unit dispatch and arrival on scene

Parallel Timelines

Parallel timelines can be used to examine multiple events that occur simultaneously. Graphic timelines can be very helpful in assembling the sequence of events that transpired, while matrix-based approaches may be helpful when several events occur at the same time.

Table 15-2 – Example of an Abbreviated Matrix Used for Developing a Timeline

The investigator may want to add columns for the police department or for accounts supplied by non-fire-service witnesses.

Creating a Timeline

The actual timeline may be created using any of several methods:

• A simple paper-and-pencil timeline may be sufficient.

• Computer software can be used to construct timelines and investigative charts.

• Some larger law-enforcement agencies may have an intelligence section whose personnel will help gather the information and then construct reference charts and reports, such as timelines.

Scaled Timeline

A scaled timeline is useful for displaying an event’s time and its chronological relationship to other events. It shows the time of each event, with the spacing between events scaled to indicate the elapsed time.

A scaled timeline may also place:

• Hard times above the line

• Soft times below the line

Figure 15-1 – A scaled timeline

The figure presents a timeline for June 15, 2001, running from 11:00 a.m. to 12:00, with these displayed events:

The figure demonstrates how verified hard times and estimated or relative soft times can be positioned together on a scaled timeline.

A timeline is a graphic or narrative representation of events related to a fire incident, arranged in chronological order.

Understanding an incident’s timeline is fundamental to failure analysis because it helps establish the sequence of events that occurred. A timeline is a comprehensive listing of specific relevant events that can be verified to a stated degree.

Timelines may include events occurring:

• Before the fire

• During the fire

• After the fire

Estimates of fire size or conditions can be valuable when developing these representations. By applying known information about fire dynamics, fire conditions may be connected to specific events. Information gathered from detection and suppression systems may also help determine:

• How the fire spread

• The times at which specific events occurred

The value of a timeline is directly related to the accuracy of its information, and its reliability depends on the level of confidence that can be placed in its elements. Not all information can be connected to a specific time; some information may need to be shown as a time interval during which the event occurred.

Timeline components may be classified as either hard times or soft times.

Hard Times

When developing a timeline, incidents that can be related to a known exact time are generally called hard times. This means the time of occurrence is specifically known.

For example, a fire department’s incident-history records may provide the exact times when units were dispatched and arrived on scene. These data can serve as benchmarks when developing the timeline.

Table 15-1 – Hard Time Sources

When collecting hard-time information, the investigator must verify that the time recorded by the source or source device is accurate.

For example, if a surveillance camera has an incorrect time when the investigator obtains its recordings, the time displayed on the recording may also be incorrect. The investigator may be able to use the current time discrepancy to determine the actual recording time. If the camera displays 4:30 p.m. when the actual time is 3:30 p.m., a recent video time-stamped 10:00 a.m. may depict activities that actually occurred at 9:00 a.m.

Soft Times

Other times may be considered soft times. A soft time is estimated or relative and is generally provided by witnesses.

A witness may be unable to state exactly when an event such as flashover occurred or when an occupant was told to leave a building. However, the witness may be able to relate the observation to another event, such as:

• The fire department’s arrival

• A particular moment in a television program

• Another identifiable event

Through interviews and further data collection, the investigator may be able to narrow the range assigned to a soft time.

Relative time is subjective and varies according to the information provided by the witness. Witnesses should refer to their actions and observations in relation to one another and should describe those relationships as specifically as possible.

Estimated time is an approximation based on information or calculations that may or may not be relative to other events or activities.

Benchmark Events

Some events are particularly valuable as foundations for a timeline or may have a significant relationship to the fire’s cause, spread, detection, or extinguishment. These are called benchmark events.

For example:

• Mr. Jones finishes his workday and punches out at 6:00 p.m.

• He begins a 25-mile drive home in heavy traffic.

• While turning onto a side street, he passes a furniture store and observes that it is closed and appears quiet.

• He later passes the fire station and sees fire trucks responding to a fire at that furniture store.

• Fire department dispatch records establish that the trucks reported their departure at 6:32 p.m.

The work time clock and fire department dispatch records establish benchmark events that may allow investigators to estimate the relative time when Mr. Jones passed the store.

Multiple Timelines

Several timelines may be needed to evaluate and document:

• The sequence of events precipitating the fire

• Events occurring during the actual fire incident

• Postfire activities

Depending on the incident’s complexity, events may be evaluated using macro or micro timelines.

A macro evaluation may cover months or years and include activities occurring long before the fire, such as:

• Building construction

• Modification of codes

• Code-enforcement activities

A micro evaluation examines a small or narrow portion of the macro timeline in detail. Examples include:

• A witness’s travel time

• The time needed to walk between rooms

• The interval between dispatch and arrival on scene

Parallel timelines may be used to examine events occurring simultaneously. Graphic timelines can help combine the sequence of events that occurred, and investigative matrices may help when several events occur at the same time.

Table 15-2 – Example of an Abbreviated Matrix Used for Developing a Timeline

The investigator may want to add columns for the police department or for non-fire service witness accounts.

Creating a Timeline

The timeline may be created using several methods. A simple paper-and-pencil timeline may be sufficient when all necessary information is available. Computer software may also be used to create timelines and investigative charts.

Some larger law-enforcement agencies have intelligence sections whose personnel assist with gathering information and then develop reference charts, reports, and timelines.

Scaled Timeline

A scaled timeline displays the time and event and their chronological relationship to other events. The time assigned to each event is shown with spacing scaled to represent the elapsed time between events.

A scaled timeline may also place:

• Hard times above the line

• Soft times below the line

Figure 15-1 – A Scaled Timeline

The illustrated timeline covers 11:00 a.m. to 12:00 on June 15, 2001.

Part 2 – System Analysis and Mathematical/Engineering Modeling

System Analysis

System analysis is an analytical approach that considers the characteristics, behavior, and performance of a variety of elements—including human activities and the mechanical features of equipment—and integrates them to provide as complete a picture as possible of the events surrounding an incident.

Simple system analyses include evaluations investigators routinely perform. For example, an informal system analysis can be used to examine a kitchen fire involving a properly functioning stove that a homeowner left on:

• One aspect of the incident concerns human factors.

• A second aspect concerns the properties of the stove and its surroundings.

• Together, these elements form the system whose combined properties led to the incident.

A variety of tools can be used to analyze an incident. Fault trees and failure mode and effects analysis provide systematic methods for analyzing systems to identify hazards or faults.

Fault Trees

Fault trees, also known as decision trees, illustrate the series of events and decisions that must occur to produce a specific outcome.

When this form of graphic logic or reasoning is applied:

• The solution may become readily apparent.

• Incorrect solutions may be eliminated from consideration.

• The diagram places the conditions and chains of events necessary for a fire or explosion into a logical sequence and position.

Similar decision trees are used in electronics and computer programming. AND and OR gates are placed at points where decisions must be made:

• At an AND gate, all listed events or conditions must be present.

• At an OR gate, any one of the listed events or conditions must be present.

Figure 15-2 – Fault tree showing the combination of “and” and “or” gates

The fault tree traces the conditions that could result in an attic fire caused by an attic ventilator:

Fault trees identify the conditions and chain of events involved in a fire or explosion. If the conditions or events did not occur in an order that would produce the event, the proposed scenario is not possible.

The investigator can assign probabilities to the events to identify their likelihood. In some cases, the final result may include multiple plausible scenarios for the fire scene.

Software for developing fault trees is readily available. Data and conditions used in fault-tree analysis or failure mode and effects analysis can be obtained from:

• Operations and maintenance manuals

• Maintenance records

• Parts-replacement and repair records

• Design documents

• Services of an expert with knowledge of the system

• Examination and testing of exemplar equipment or materials

• Component-reliability databases

• Building plans and specifications

• Fire department reports

• Incident-scene documentation

• Witness statements

• Medical records of victims

• Human-behavior information

Failure Mode and Effects Analysis

Failure mode and effects analysis (FMEA) is another graphic method used to determine the causes and effects associated with an event or a subevent leading to a fire.

By identifying specific components associated with potential ignition sources or fire spread, it may be possible to identify:

• Specific predecessor events that occurred

• Activities that preceded the incident

The investigator completes an FMEA table using column headings appropriate to the particular investigation. Although the headings are flexible, each FMEA contains at least:

• The item or action being analyzed

• The basic fault, failure, or error that created the hazard

• The consequences of the failure

An FMEA table can be either highly involved or quite simple, depending on the incident’s complexity or the required depth of analysis.

When compiling FMEA information:

• Consider the environmental conditions for each item or action.

• Consider the process status for each item or action.

• Probabilities or degrees of likelihood can be assigned to each occurrence.

• The table’s accuracy depends on identifying the system components and human actions relevant to the incident.

Tip: The minimum information for an FMEA includes a list of all system components and human actions that may have led to the incident, the possible failure modes for each component and action, and the immediate consequences of each failure.

Mathematical/Engineering Modeling

Mathematical or engineering modeling of fire incidents is generally performed by:

• Using calculations or formulas to evaluate specific issues

• Using computer-aided analysis to examine more complex fire dynamics and fire progression

Fire-modeling software is widely available.

One group of modeling techniques applies engineering models. Data are developed that incorporate:

• Known and approximated properties of materials and systems

• Specific features and components of the fire incident

• Physical-property estimates defined to a stated degree of certainty

Accepted engineering and analytical techniques are then applied to the assumed facts or modeling input data. The resulting model develops descriptions of what may or may not have occurred under a clearly stated set of conditions.

Mathematical or engineering models can be as simple as manually calculating flammable-gas concentrations to determine the upper and lower explosive limits for a gas in a given space.

Other models may be much more complex, such as those used for fire-growth modeling. These models may apply zone or finite-element techniques that must be run by a qualified modeler using a well-equipped personal computer.

Figure 15-3 – Fire growth curves

The figure depicts heat-release curves associated with National Fire Protection Association standard fire-growth rates. The surrounding discussion identifies slow, medium, fast, and ultrafast fire-growth rates.

Using Models in an Investigation

These modeling techniques are tools used to test a hypothesis. Repeated calculations should be performed to bracket the conditions that most likely existed during the incident.

This type of modeling can be used to determine the most probable scenario for a stated set of boundary conditions. Models do not necessarily provide a definitive solution.

As with all evidence, model results should be considered together with the other data gathered during the fire investigation.

Models can frequently be used to:

• Support a particular hypothesis

• Disprove a particular hypothesis

Even when the fire’s origin and cause are not in question, a fire model may be useful in understanding fire damage or injury.

The use of analytical tools may depend on:

• The scope of the investigator’s role in the particular investigation

• The practical purpose of the question being examined

A special expert may be needed to complete the analysis.

Various disciplines use mathematical models to simulate or predict events through established scientific principles and empirical data. In some cases, these models have provided useful information in fire or explosion investigations.

Limitations of Mathematical/Engineering Modeling

Mathematical or engineering modeling—whether it uses hand calculations or computer-based fire models—has limitations and depends on assumptions that the investigator must consider.

Models are useful for testing hypotheses but should never be used as the sole basis for determining a fire’s origin and cause.

Mathematical-model results may be affected by several factors:

• Model inputs are subject to uncertainties.

• Standardized methods of selecting model inputs can narrow these uncertainties.

• Generic data from fire-science literature or exemplar models are often used and may contribute to uncertainty.

• Approximations within the model itself also create uncertainty in the results.

When using a model, retain the original input and output files as part of the investigative record. This allows other interested parties to examine the complete contents of the work product.

Mathematical modeling must be performed by someone with sufficient training and experience to conduct the required type of analysis.

Mathematical or engineering modeling of fire incidents is generally conducted by:

• Using calculations or formulas to evaluate specific issues

• Using computer-aided analysis to examine more complex fire-dynamics and fire-progression issues

Fire-modeling software is widely available.

One group of modeling techniques applies engineering models. The data developed for these models incorporate:

• Known and approximated properties of materials and systems

• Specific features and components of the fire incident

• Physical-property estimates defined to a stated degree of certainty

Accepted engineering and analytical techniques are then applied to assumed “fact sets” or “modeling input data.” The purpose is to develop descriptions of what may or may not have occurred under a clearly stated set of conditions.

Mathematical models vary considerably in complexity:

• A simple model may use a manual calculator to calculate a flammable-gas concentration and determine the upper and lower explosive limits for a particular gas in a particular space.

• More complex models may examine fire growth using zone or finite-element techniques. These models must be operated by a qualified modeler using a well-equipped personal computer.

Figure 15-3 – Fire Growth Curves

Figure 15-3 presents heat-release graphics for the NFPA standard slow, medium, fast, and ultrafast fire-growth rates.

The curves show heat-release rate increasing with time at different rates of fire growth.

Use of Mathematical/Engineering Models

These techniques are tools for testing hypotheses. Repeated calculations should be performed to bracket the conditions most likely to have existed during the incident.

Modeling may be used to determine the most probable scenario for a specified set of boundary conditions. However, models do not necessarily provide a definitive solution. Their results must be considered together with the other data gathered during the fire investigation.

Models can frequently help:

• Support a hypothesis

• Disprove a hypothesis

• Explain fire damage or injury, even when the fire’s origin and cause are not in question

• Simulate or predict events using established scientific principles and empirical data

The suitability of these analytical tools may depend on:

• The scope of the fire investigator’s role in the investigation

• The practical purpose of the question being examined

A special expert may be required to complete the analysis.

Limitations of Mathematical/Engineering Modeling

Mathematical modeling—whether performed through hand calculations or computer-based fire models—has limitations and relies on assumptions that the investigator must consider.

These models are useful for testing hypotheses, but they should never be used as the sole basis for determining a fire’s origin and cause.

Model results may be affected by several sources of uncertainty:

• Model inputs are subject to uncertainty, although standardized input methods for the selected model can narrow that uncertainty.

• Generic data obtained from fire-science literature or exemplar models may contribute additional uncertainty.

• Approximations made within the mathematical model itself create uncertainty in the results.

When using a model, retain the original input and output files as part of the investigative record. Retaining these files allows other interested parties to examine the complete work product.

Mathematical modeling must be performed by an individual with sufficient training and experience to conduct the required type of analysis.

Part 3 – Specialized Aalyses, Fire Dynamics, Graphic Representations, and Fire-Model Selection

Heat Transfer Analysis

Heat-transfer models allow an investigator to determine how heat moved from a source to a target through one or more of the three heat-transfer modes:

• Conduction

• Convection

• Radiation

These models can be used to test hypotheses concerning matters such as whether a particular heat source was competent to act as an ignition source in a given fire scenario.

Other useful applications include explaining:

• Damage to or ignition of adjacent buildings caused by fire spread

• Ignition of secondary fuel items

• Transmission of heat through building elements

Flammable Gas Concentrations

By determining the concentration of a gas within a particular space, an investigator can support or disprove a hypothesis that the presence of flammable gas contributed to the incident’s sequence of events.

Flammable-gas concentration results can also support or refute hypotheses concerning:

• The location of a leak

• The size of a leak

• The competency of an ignition source

Hydraulic Analysis

When a fire is not controlled by an operating sprinkler system, it is important to determine:

• Whether the sprinkler system functioned as designed and intended

• Whether the system’s design was adequate for the particular occupancy and the furnishings present

Analysis of the sprinkler system and its water supply should determine whether both were properly matched to the hazard being protected.

Questions should be asked to determine whether the system contained faults such as:

• Closed valves

• Faulty sprinklers

It may also be necessary to evaluate an apparently functional system that did not control the fire. This evaluation involves analyzing:

• Water-supply characteristics

• Water flow through the piping network

• Sprinkler-discharge characteristics

The investigator may also need to develop a fire-growth or heat-release model to assess the sprinkler system’s potential effectiveness under the conditions involved.

Hydraulic analysis can be used with a variety of fire-protection systems, including:

• Wet systems

• Dry systems

• Antifreeze systems

• Carbon-dioxide systems

• Gaseous-suppression-agent systems

• Dry-chemical systems

• Fuel-distribution systems

Thermodynamic Chemical Equilibrium Analysis

Fires and explosions believed to have been caused by reactions involving known or suspected chemical mixtures can be investigated by conducting a thermodynamic analysis of:

• The probable chemical mixtures

• Potential contaminants

Thermodynamic analysis can be used in incidents involving chemical reactions and to determine whether a proposed scenario is feasible.

This analysis may be useful when evaluating:

• Hypothetical combustion reactions

• The role of contamination

• The role of ambient conditions

• The potential for overheating

• Other related scenarios

Computer programs can make predictions from input data describing the properties of the chemicals involved.

An analysis might show that the chemicals would not produce a thermodynamic reaction, allowing that hypothesis to be eliminated. Alternatively, it might show that the chemicals are capable of being thermodynamically favored. In that case, further investigation would be required to determine whether their reaction would be sufficient to cause ignition.

Structural Analysis

Structural analysis can provide clues explaining why a building collapsed at a particular point during a fire.

This type of analysis can be critical in directing the investigator toward the area where the fire had the most significant effect on the building’s structural strength.

Structural analysis normally requires the services of an engineer trained in failure analysis.

Egress Analysis

Determining why a fire victim did not escape from a particular fire scene is a critical question for the fire investigator.

The failure to escape may be related to:

• The building’s egress design, or lack of an adequate design

• Maintenance issues

The investigator should obtain information such as:

• Locations of exits

• Egress routes

• Travel distances

• Egress-route widths

Some computer-based fire models contain modules that can assist with this analysis. For example, the National Institute of Standards and Technology’s (NIST’s) Consolidated Model of Fire and Smoke Transport (CFAST) contains modules that can provide egress data for the specific fire situations they can model.

Fire Dynamics Analysis

Several methods are available to assist with the analysis of fire dynamics and fire growth, including:

• Specialized fire-dynamics routines, such as hand calculations

• Computer models, including zone models and field computational fluid dynamics (CFD) models

These analytical methods can be used to:

• Test and evaluate hypotheses concerning origin and cause

• Assist in evaluating physical evidence

• Assist in evaluating eyewitness evidence

• Support the hypothesis-development process

Computer models based on established mathematical equations may be useful in predicting fire-related factors and events, including:

• Time to flashover

• Gas temperatures or concentrations

• Flow rates of fire-related gases

• Temperatures of interior surfaces

• Time of activation of fire-detection and suppression devices

• Effects of events such as opening doors and windows

Computer models can be useful tools when evaluating an investigator’s hypothesis. When known input data are used, model results can be compared with witness accounts and physical evidence to test:

• The investigator’s hypothesis

• A witness’s account

Caution: These models are only tools and are subject to limitations based on uncertainties that must be assessed and analyzed. Although models can provide additional fire data, their results must be weighed against:

• Other information gathered during the investigation

• The reliability of the input data

• The assumptions made

Tip: Fire dynamics and fire growth can be analyzed using several methods, including:

• Specialized fire-dynamics routines, such as hand calculations

• Computer models, such as zone models and field CFD models

Variables or uncertainties that can influence fire-modeling results include:

• Fire-load characteristics

• Ventilation openings, including their size and whether they are open or closed

• Heating, ventilation, and air-conditioning (HVAC) flow rates

• Heat-release rates

Specialized Fire Dynamics Routines

Specialized fire-dynamics routines are simplified procedures that require minimal data to run a computer model and can often answer a narrowly focused question.

These procedures commonly use specific algebraic hand-calculation equations and generally require much less data and information than more complex models.

The equations used in these routines:

• Have been derived through research and experimentation

• Require input variables developed from information obtained at the fire scene or from an appropriate reference material

The equations and hand calculations used in fire-dynamics routines can evaluate specific issues, including:

• Time to flashover

• Heat flux

• Heat-release rate

• Time to ignition

• Flame height

• Detector activation

• Gas concentration

• Flow rates of smoke, gas, and unburned fuels

Computer Fire Models

The two primary types of computer models used to assess fire growth are:

• Zone models

• Computational fluid dynamics models

Computer models allow more complex and detailed analysis of fire growth and behavior. They are useful for:

• Predictive analysis and testing

• Postincident investigation

• Hypothesis testing

These models incorporate assumptions that must be considered when analyzing their results, and the models are subject to limitations.

Zone Models

Zone models usually divide a compartment into two zones:

• A hot upper zone

• A cooler lower zone

They assume that universal conditions prevail throughout each zone and allow for the zones to expand during the course of a fire.

Zone models are often run on personal computers and are generally well accepted and validated through peer review.

Computational Fluid Dynamics Models

Computational fluid dynamics models are more complex than zone models and divide a compartment into many small cells.

The model performs numerous calculations within each cell, and activity in one cell affects the surrounding cells. This produces a more detailed analysis of the fire event but also requires a much greater level of expertise to use correctly.

CFD models:

• Require greater computer capabilities

• Can be run on a personal computer

• Are especially useful when evaluating fire progression involving irregular geometry

• Can be used when very fine detail is required

The use of CFD models in fire investigation and litigation is increasing.

Graphic Representations

Graphic representations are another useful way to show what occurred during a fire incident. They include:

• Drawings

• Physical models

• Computer animations

Some computer models also use graphic interfaces that permit visual representation or interpretation of the data produced by the model.

For example, NIST’s Fire Dynamics Simulator is a CFD model that works with NIST’s SmokeView program to provide a visual animation of fire progression. Fire Dynamics Simulator is a large-eddy simulation code for low-speed flows, with an emphasis on smoke and heat transport from fires.

Graphic representations are frequently used by investigation teams and forensic-evaluation personnel. They may be used to:

• Help the investigation team understand an incident location

• Assist with interviewing witnesses

• Define and identify materials and systems and their involvement in the incident

• Help a judge or jury understand important fire-scene features

• Explain the underlying scientific and engineering principles that produced a particular fire outcome

Graphic representations should not be confused with mathematical models:

• Mathematical models are based on calculations.

• Graphic representations are based on geometric representations of a scene or a set of facts.

Modern modeling programs permit the operator to test the effects of changes in fire conditions by:

• Opening or closing doors and windows

• Changing furnishings

• Obstructing flow paths with victims

• Incorporating weather conditions

• Making numerous other changes to examine their effects on fire behavior

Guidelines for Selection and Use of a Fire Model

Numerous factors should be considered when selecting a fire model for a particular incident.

The selection process begins by:

1. Identifying the hypothesis or hypotheses to be tested or the other questions the modeling procedure must answer.

2. Validating any model chosen on a preliminary basis. Information for validation should be available from the model developer and in the model’s documentation.

3. If possible, considering the degree of uncertainty expected from:

   • The model itself

   • The data entered into the model

Figure 15-4 – Fire model selection flowchart

The flowchart presents the following model-selection process:

1. Start

2. Define problem

3. Select candidate model

4. Ask: Candidate exist?

   • No: Ask whether the problem can be redefined.

     • Yes: Return to Define problem.

     • No: Using a computer model will require model development, and the process ends.

   • Yes: Continue to Evaluate V & V.

5. Ask: Model suitable?

   • No: Return to Select candidate model.

   • Yes: Continue to Perform analysis.

6. Determine uncertainty and user effects

7. Ask: Analysis suitable?

   • No: Return to Select candidate model.

   • Yes: Continue to Confirm basis for selection.

8. End

Determining why a fire victim failed to escape from a fire scene is a critical question for the fire investigator.

The failure to escape may be related to:

• The building’s egress-design features

• A lack of appropriate egress features

• Maintenance issues

The investigator should obtain relevant data, including:

• Locations of exits

• Egress routes

• Travel distances

• Egress-route widths

Some computer-based fire models have modules that provide egress data for the specific fire situations being modeled. One example is the National Institute of Standards and Technology’s (NIST’s) Consolidated Model of Fire and Smoke Transport (CFAST).

Part 4 – Fire Testing and Data Required for Modeling and Testing

Fire Testing

Fire testing is a process that can help:

• Verify collected data

• Test a specific hypothesis

Testing can be conducted:

• In the field

• In a controlled environment

• Through tests ranging from bench tests to full-size recreations of the event

Fire testing is useful for determining factors or events associated with a fire, including:

• Origin and cause

• Fire spread

• Combustion characteristics

• Effects of fire on materials

When performed properly, fire testing can be useful in evaluating a hypothesis. However, the investigator must remain aware of potential differences and inaccuracies between the test conditions and the conditions that existed during the actual fire.

Differences may involve:

• Weather conditions

• Missing windows or loss of glass

• Fuel loads associated with contents

• Ventilation effects

Fire testing may be used as a tool to examine a hypothesis, but the resulting data should not be relied on as absolute. Testing can provide useful information, but every condition from a particular fire cannot be recreated perfectly.

To the extent possible:

• Testing methods should follow accepted norms of practice.

• Testing procedures should follow accepted norms of practice.

• Testing instruments should follow accepted norms of practice.

Following established practices will help ensure the credibility of the test results.

Examples of fire testing include:

• Determining the burn-through time of a wall or door using recognized fire-endurance testing techniques, such as those in ASTM E119-20, Standard Test Methods for Fire Tests of Building Construction and Materials

• Testing the heat-release characteristics of a piece of cushioned furniture to assess whether it could have been responsible for the fire-growth and damage patterns observed

Applying data developed through testing can provide invaluable information supporting or refuting the hypotheses under evaluation. Nevertheless, fire testing has limitations because every aspect of a particular fire cannot be recreated.

Figure 15-5 – A fire’s progression over a 4-minute period

The figure presents a series of images showing four minutes of fire progression before extinguishment.

The fire was initiated by using a single match to ignite one sheet of newspaper.

Figure 15-6 – Temperature development during ASTM E1537-16 fire testing of a couch

Temperature measurements were taken at locations:

• 4 ft (1.2 m) above the couch

• Directly above the back of the couch

The graph is titled Thermocouples and includes:

The figure plots the two thermocouple temperature traces over the duration of the test.

Data Required for Modeling and Testing

To conduct valid modeling and testing, it is important to gather data that are as accurate and complete as possible.

The “garbage in, garbage out” principle applies: modeling or testing results can be no more reliable than the information from which they are developed.

It should be anticipated that, during court proceedings:

• Test results will be subject to a Daubert review.

• The results presented will be only as valid and accurate as the information from which they were derived.

• Their validity and accuracy will also depend on the care taken in developing them.

The textbook refers to Chapter 5, Legal Considerations for Fire Investigators, for additional information concerning the Daubert rule.

Important modeling and testing information includes:

• Structural information

• Information about materials and contents

• Ventilation information

Structural Information

Structural information should address room dimensions and the sizes of structural components as they apply to the fire scenario.

The information should include:

• Length, width, and height of rooms and buildings

• Wall thickness

• Slopes of floors and/or ceilings

• Construction materials, including wall coverings

• Construction features present, such as:

  • Types of doors

  • Windows

  • HVAC systems

  • Stair locations

Materials and Contents

A meaningful fire analysis requires an understanding of:

• Heat-release rate

• Fire-growth rate

• Total heat released

This analysis should be documented and should include:

• Type of contents, including materials

• Location of contents

• Configuration and condition of contents

Ventilation

Understanding ventilation conditions is important to the validity of a fire test or model.

Information concerning the positions and conditions of openings should be included, along with:

• Locations of openings

• Sizes of openings

• Status of openings—open or closed

• Area of usable opening—fully open, partially open, or closed

• Ventilation effects, including wind and HVAC

• Fire department operations

Valid modeling and testing require data that are as accurate and complete as possible. The “garbage in, garbage out” concept applies.

During court proceedings, test results should be expected to undergo a Daubert review. The presented results will be only as valid and accurate as:

• The information from which they were developed

• The care taken when developing them

Chapter 5, Legal Considerations for Fire Investigators, provides additional information about the Daubert rule.

Important information for modeling and testing includes:

• Structural information

• Information about materials and contents

• Ventilation information

Structural Information

Structural information includes room dimensions and the sizes of structural components as they relate to the fire scenario.

The collected information should include:

• Length, width, and height of rooms and buildings

• Wall thickness

• Slopes of floors and/or ceilings

• Construction materials, including wall coverings

• Construction features, including types of doors, windows, HVAC systems, and stair locations

Materials and Contents

A meaningful fire analysis requires an understanding of:

• Heat-release rate

• Fire-growth rate

• Total heat released

The analysis should be documented and include:

• Types of contents, including their materials

• Locations of contents

• Configuration and condition of contents

Ventilation

Understanding ventilation conditions is important to the validity of a fire test or model.

Data concerning the positions and conditions of openings should include:

• Locations of openings

• Sizes of openings

• Status of openings as open or closed

• Area of usable opening, whether fully open, partially open, or closed

• Ventilation effects, including wind and HVAC

• Fire department operations

Part 5 – Incendiary Fires and Incendiary Fire Indicators

Incendiary Fires

An incendiary fire is a fire that is intentionally ignited in an area or under circumstances where and when a fire should not occur.

Indicators of an incendiary fire may include:

• Indicators directly related to combustion

• Other evidentiary factors not directly related to combustion, such as suspect development and identification

Incendiary Fire Indicators

The indicators in this section should be examined for their possible support of the hypothesis that a fire is incendiary.

An individual indicator does not automatically establish an incendiary cause. Each indicator must be evaluated within the complete fire scene and investigation.

Multiple Fires

Multiple fires are fires with no obvious connection that would have allowed one fire to ignite the fuel in—or spread to—another area.

For example, a basement fire that spreads through the walls of a balloon-frame house to the attic would not be classified as an incident involving multiple fires. In that situation, the fire spread naturally through a vertical opening and ignited combustible materials in a location remote from the initial fire.

Before identifying an additional fire as a separate fire, the investigator must determine that it was not the natural result of the growth and spread of the initial fire.

Other natural means of fire spread that can create multiple fires, or the appearance of multiple fires, include:

• Conduction, convection, or radiation

• Flying brands

• Direct flame impingement

• Falling flaming materials, or drop-down, such as curtains

• Fire spread through shafts, such as pipe chases or air-conditioning ducts

• Fire spread within wall or floor cavities in balloon construction

• Heat from a fire accumulating at the ceiling level and igniting other materials near the ceiling

• Overloaded electrical wiring

• Utility-system failures

• Fuel-gas or dust explosions

• Lightning

• Rupture and launching of aerosol containers

An investigator should not confuse the site of a previous fire with the site of a more recent fire. Doing so could produce the erroneous hypothesis that multiple fires occurred simultaneously. The structure’s fire history should be obtained and examined.

Apparent multiple points of fire can also result from:

• Sustained burning or smoldering during or after fire suppression or overhaul

• Full-room involvement

• Post-flashover conditions

Full-room involvement or post-flashover conditions can make the identification of multiple fires more difficult or impossible.

It is important to conduct a complete scene examination to determine whether separate fires occurred and to establish areas with lesser or greater damage and fire-spread patterns.

If a complete scene examination is not performed:

• Valuable evidence may not be identified.

• The investigator may be unable to determine accurately whether separate fires occurred.

Where permitted, the investigation should include a complete examination of areas within the subject structure that do not appear to have been damaged by fire.

Trailers

A trailer is a deliberately introduced fuel or a manipulation of existing fuel used to assist fire spread from one area to another. One fire then ignites other areas through the trailer.

Figure 15-7 – Here, paper towels were used (unsuccessfully) as a trailer

The figure shows paper towels that were used unsuccessfully in an attempt to spread a fire as a trailer.

Trailers can leave distinctive patterns on horizontal surfaces such as floors. However, when the floor has been cleared of debris and the pattern can be seen easily, it is important to determine whether the pattern actually resulted from another mechanism or material.

Other possible causes of trailer-like patterns include:

• Open areas bordered by protected areas

• Effects of flashover

• Effects of full-room involvement

• The interaction of radiant heat with carpet and carpet padding

When a room becomes fully involved, radiant heat can create floor patterns that may be misinterpreted as trailer-burn patterns.

Materials that can be used as trailers include:

• Ignitable liquids

• Clothing

• Paper

• Straw

Many common household products, including cleaning fluids and gasoline, are ignitable liquids. Their presence at a fire scene is not necessarily evidence that they were used as a trailer.

It is not the fuel itself that makes a trailer; it is the manner and location in which that fuel was used.

Lack of Expected Fuel Load

When the observed fire damage is inconsistent with the observable fuel load, further investigation is warranted.

The investigator should attempt to quantify the fire damage expected from the known or reported fuel load and compare it with the observed fire damage. However, the absence of an expected fuel load is not sufficient by itself to classify the fire cause as incendiary.

Areas that routinely contain low or limited fuel loads include:

• Corridors

• Stairways

• Hallways

• Vacant homes

If the fire’s origin is in a low-fuel or limited-fuel area, the investigator should look for physical evidence of fuels, such as:

• Ignitable liquids

• Samples indicating the presence of an ignitable liquid

Burning in these areas may not be unusual if it represents fire extension or movement from another area, particularly when the adjacent space has developed past flashover.

Lack of Expected Ignition Sources

The absence of a readily apparent competent ignition source at the fire’s origin is another indicator that deserves further investigation.

Investigators may need to search the debris closely for ignition sources that may have:

• Burned

• Melted

• Been consumed

Closets, crawl spaces, and attics are typical areas in which only a limited number of heat sources are normally present.

Investigators should examine all fire-damaged areas in their entirety and should not focus only on the area showing the greatest fire damage.

Areas of heavy burning can be influenced by:

• Products with high heat-release rates

• Delayed extinguishment

• Ventilation effects

These factors are not specific indicators of the fire’s area of origin.

Exotic Accelerants

Mixtures of fuels containing Class 3 or Class 4 oxidizers and thermite mixtures may be considered exotic accelerants.

Some oxidizers are capable of self-ignition. These accelerants can produce exceedingly hot fires and generally leave residues that may be identified visually or chemically.

Indicators of these substances, sometimes called high-temperature accelerants (HTAs), include:

• Rapid rate of growth

• Brilliant flares

• Melted steel or concrete

Other explanations for dramatic fire effects and patterns should always be considered, including:

• Ventilation effects

• Delays in fire suppression

• Effects of particular fire-suppression tactics

• Type and configuration of fuels

Forced Entry

Evidence of forced entry may include:

• Broken door frames and locks

• Broken windows

• Pry marks

Entry points should be carefully examined and documented for potential physical evidence.

Firefighters and other suppression personnel may have forced entry while responding to the fire. The investigator should interview these personnel to determine whether they forced entry.

In some cases, forced-entry evidence may indicate a burglary. In other cases, the property owner or resident may have staged the evidence in an attempt to mislead the investigation.

Signs of forced entry may also have originated during an earlier event unrelated to the fire.

Unusual Fuel Load or Configuration

A fire-setter may attempt to produce more aggressive or effective burning by moving contents or materials into a configuration that permits faster fire growth or fire spread than would be expected if the contents remained spaced farther apart.

This may also be done in an attempt to produce more complete burning of the fuels. Witnesses may be able to provide information concerning the positions or locations of contents before the fire.

The types of fuels can be evaluated to determine whether they would ordinarily be expected within the particular occupancy because fuels may be added to an area to assist fire growth or spread.

An unusual fuel load or configuration should not automatically be assumed to be related to the fire cause. If the load appears genuinely unusual, the investigator should seek additional information from:

• The occupant

• The first-arriving engine company

This information can help determine whether the load or configuration is abnormal or has a rational explanation.

Burn Injuries

Whenever victims experience burn injuries during a fire, those injuries should be analyzed to determine whether they provide information concerning the fire’s cause.

The investigator should determine:

• The circumstances surrounding the injury

• If possible, whether the injury itself indicates how it was received, such as contact with a hot object or exposure to an open flame

Because burn injuries may be sustained while a person is setting an incendiary fire, local hospitals should be contacted to identify recent burn victims. Some jurisdictions require burn injuries to be reported.

A detailed interview with a burn victim may help determine:

• The fire’s origin

• The fire’s cause

• The fire’s spread

• The victim’s activities before and during the fire

The information can be compared with physical findings from the scene to determine whether the accounts are consistent.

All burn injuries should be documented. When appropriate, samples of a victim’s clothing may be taken for laboratory testing for ignitable liquids.

Incendiary Devices

Incendiary devices include a wide range of mechanisms used to initiate an incendiary fire. If such devices are used, their remains can often be found at the scene.

Almost any appliance or heat-producing device can be used as an incendiary device. If no other obvious ignition sources are present, efforts should be made to determine whether a device was used.

Examples include:

• A combination of a cigarette and matchbook

• Candles

• Wiring systems

• Electric heating appliances

• Fire bombs or Molotov cocktails

• A paraffin wax–sawdust incendiary device, such as fireplace starters

Figure 15-8 – This heater was used as an incendiary device

The figure identifies a heater that was used as an incendiary device.

Figure 15-9 – Fire bombs are also referred to as Molotov cocktails

The figure identifies the alternative term Molotov cocktails for fire bombs.

Delay Devices

Some incendiary devices are constructed as delay devices to:

• Give the fire-setter enough time to leave the area safely

• Help the fire-setter establish an alibi

If the investigator discovers a device that has not activated, it should not be moved.

If an active or live device is found, adequate precautions and safeguards should be taken, including:

• Evacuating the area

• Notifying trained explosive-ordnance-disposal personnel

Figure 15-10 – An example of a time-delayed incendiary device

The figure identifies an example of an incendiary device designed to delay ignition.

Appliances Used to Mask the Fire’s True Cause

A fire-setter may attempt to conceal the fire’s true cause by placing an appliance within the scene so that it can be identified as the “obvious” cause.

For example, a fire-setter may pour an ignitable liquid into a coffeemaker and cause a fire. The investigator should not assume that the fire resulted from an appliance malfunction. Additional testing or evaluation may be warranted to determine the fire’s true cause.

It is important to remain aware of spoliation issues when conducting this type of investigation. If investigators lack the required engineering training, they should obtain qualified assistance.

For example, a pot-on-the-stove fire may produce severe damage to some or all of the appliance’s controls, making examination impossible without removing the cooktop surface. Because the components are largely made of phenolic plastic:

• Much of the material may be heavily damaged.

• Removing the control panel’s back panel can cause the contacts to collapse and fall apart.

Caution should be taken to protect these mechanisms until:

• All interested parties have been notified.

• Those parties have had an opportunity to be present before destructive testing occurs.

As an alternative to destructive testing, an X-ray machine can be used to document the positions of the controller contacts without disassembling the panel.

These spoliation considerations apply to preservation and destructive examination of the appliance or device; they are not limited to explosion investigations.

Searching for Additional Fires or Devices

Because arsonists may set multiple fires, the investigator should examine the entire fire building to determine whether other fires with separate origins occurred.

An arsonist may have used similar devices in other fires, providing valuable clues. Examine these areas for debris that may contain:

• Delay devices

• Other incendiary devices

• Evidence of ignition methods that contributed to the ignition sequence

When multiple fires have occurred, at least one incendiary device has often failed to operate, leaving the investigator valuable evidence.

Investigators should also look for trailers leading from one burned area to another.

Tip: During investigations of possible arson fires, you should work closely with law-enforcement and prosecuting authorities.

Some incendiary devices are constructed as delay devices to give the fire-setter time to:

• Leave the area safely

• Establish an alibi

If an investigator discovers a device that has not activated, it should not be moved.

If an active or live device is found:

• Evacuate the area.

• Take appropriate precautions and safeguards.

• Notify trained explosive ordnance disposal personnel.

Figure 15-10 – Time-Delayed Incendiary Device

Figure 15-10 shows an example of a time-delayed incendiary device.

Attempts to Mask the Fire’s Cause

A fire-setter may place an appliance at the scene to create an apparently obvious explanation for the fire.

For example, a fire-setter may pour an ignitable liquid into a coffeemaker, causing a fire that appears to have resulted from an appliance malfunction. The investigator should not automatically assume that the appliance caused the fire. Additional testing or evaluation may be necessary to determine the fire’s true cause.

Protecting Potential Device Evidence

Investigators must remain aware of explosion-related issues during this type of investigation. Investigators who lack the necessary engineering training should seek qualified assistance.

For example, a pot-on-the-stove fire may heavily damage some or all of the control mechanisms on the panel at the upper rear portion of the cooktop. Because many of these components are made largely from phenolic plastic:

• The components may be heavily damaged.

• Removing the rear panel may cause electrical contacts to collapse and fall apart.

These mechanisms should be protected until:

• All interested parties have been notified.

• The interested parties can be present before destructive testing occurs.

An X-ray machine may be used as an alternative to destructive testing to document the controllers’ contact positions without disassembling the panel.

Searching for Additional Devices and Fires

Because arsonists may set multiple fires, investigators should examine the entire fire building to determine whether other fires with separate origins occurred.

A fire-setter may have used similar devices in other fires, providing investigative clues. Examine the scene for debris that may contain:

• Delay devices

• Other incendiary devices

• Evidence of methods contributing to the ignition sequence

In multiple-fire incidents, at least one incendiary device may fail to operate and leave valuable evidence.

Investigators should also look for trailers extending from one burn area to another.

Tip: During investigations of possible arson fires, work closely with law-enforcement and prosecuting authorities.

Part 6 – Ignitable Liquids, Fire Growth, and Potential Indicators Not Directly Related to Combustion

Presence of Ignitable Liquids in the Area of Origin

The presence of an ignitable liquid in an unusual or unexpected location may indicate that a fire was incendiary. Care should be taken to document where the ignitable liquid was found.

The location and pattern must be evaluated in context:

• A perceived ignitable liquid on the floor of a garage may not be unusual because vehicles, lawn equipment, and fuel cans may be stored there.

• An ignitable liquid found on a kitchen floor in a random linear pattern should be considered as a possible result of an intentional act or an ignitable liquid trailer.

It is the investigator’s responsibility to determine whether the liquid’s presence resulted from intentional placement intended to:

• Start the fire

• Accelerate the fire

• Spread the fire

Samples of the debris should always be taken for laboratory analysis.

Laboratory confirmation of an ignitable liquid is a critical step when the investigator’s cause hypothesis includes the application of such a liquid. Confirmation can help substantiate a criminal case.

Use of Ignitable Liquid Detection Canines

An ignitable liquid detection canine, called an IGL canine in NFPA 921, is specially trained to detect various ignitable liquids and can provide useful assistance in identifying areas of the fire scene that may contain them.

Although these dogs have been called accelerant-detection canines, the word accelerant should be avoided. That term suggests a person intentionally placed an ignitable liquid in a particular location. An IGL canine detects the presence of a liquid but does not identify the intent behind its presence.

Figure 15-11 – An ignitable liquid detection canine may be a useful addition to a fire investigation

The figure identifies an IGL canine as a potentially useful investigative resource.

Training and Reliability

An IGL canine’s abilities and reliability depend on:

• The canine’s training

• The handler’s training

• The continued training received by both

The investigator should be familiar with the handler and with the training that the canine has received and continues to receive.

An IGL canine–handler team:

• Should be certified by an appropriate certifying body

• Must undergo periodic proficiency assessments

The fire investigator should use an IGL canine together with:

• Other investigative and analytical methods

• The investigator’s training and experience

• Information discovered during the case

If the investigation indicates that a sample should be collected from a particular area, the collection can and should be performed even if the area did not produce a positive canine alert.

Conversely, a canine alert in an area is not conclusive proof that an ignitable liquid is present there.

IGL canines have a reputation for producing few false-positive indications, but their ability to distinguish ignitable liquids from common background materials in buildings is more important.

This requirement separates IGL canines from other law-enforcement dogs trained to detect unusual substances such as drugs or bombs. An IGL canine must be trained not to alert to common petroleum-based substances, including:

• Burned plastic

• Burned carpet

Using an IGL Canine During an Investigation

To use an IGL canine during an investigation:

1. Perform the normal investigative steps to identify areas where an ignitable liquid may have been used.

2. Brief the canine-handler team on:

   • The areas to be examined

   • Any safety hazards within those areas

3. Allow the handler to enter the identified areas and seek locations where the canine alerts to a potential ignitable liquid.

4. The handler identifies alert locations using a token or another item.

5. The investigator, with input from the handler when appropriate, collects:

   • Fire debris

   • Other evidence for laboratory examination

6. If possible, before sealing the evidence containers:

   • Place the cans containing collected fire debris and the cans containing comparison-sample materials out for review by the canine.

   • Determine whether the canine continues to alert to the evidence after it has been collected.

Every substance collected because of an IGL canine alert must be validated through laboratory analysis. Without laboratory validation, it should not be used as evidence that the substance was present in a criminal or civil court proceeding.

Assessment of Fire Growth and Damage

If a fire spreads more rapidly than can be explained by the expected fuel load, or spreads beyond the area where it would normally be expected to remain confined, the investigator should examine more closely the factors that may have contributed to the fire’s growth.

Fire growth depends on several variables, including:

• Volume of the compartment

• Ceiling height

• Heat-release rates of the fuels

• Location of the initial fuel package within the compartment

• Location of subsequent fuel packages

• Ventilation

In the absence of physical evidence, an investigator is cautioned against relying on subjective descriptions such as:

• Excessive

• Abnormal

• Unusual

• Suspicious

Such descriptions should not be used by themselves to support an incendiary-fire cause determination.

Proper use of a fire model can assist in determining the accuracy of the investigator’s observations.

Potential Indicators Not Directly Related to Combustion

Certain indicators can help an investigator develop:

• An ignition hypothesis

• Questions for witnesses

• Additional avenues of investigation

These indicators generally do not directly establish the fire’s cause. Instead, they tend to show the possibility that someone had prior knowledge of the fire.

Remote Locations With a Blocked or Obstructed View

A fire-setter may start a fire in:

• A remote location

• A location obscured from public view

Of greatest importance are actions taken shortly before the fire to obstruct the view, such as:

• Newly covered windows

• Newly painted windows

• Furniture placed in front of exterior openings

These findings can provide information helpful in:

• Establishing timelines

• Questioning witnesses

Accidental fires can also begin in remote locations. Therefore, no cause-determination conclusion should be based solely on the location of origin.

Fires Near Service Equipment and Appliances

To make a fire appear accidental, a fire-setter may set a fire near an appliance in the hope that the appliance will be assumed to be the ignition source.

Each appliance should be carefully evaluated to determine whether it was actually the ignition source.

Issues related to spoliation should be considered before conducting any destructive evaluation.

Tip: Always strive to perform investigations systematically. Establish a normal routine for every fire investigation so that investigations will eventually be conducted automatically in the same manner, consistent with NFPA 921, Guide for Fire and Explosion Investigations, Sections 4.2 and 4.3.

Removal, Replacement, or Absence of Contents Prior to the Fire

Contents are sometimes removed or replaced with items of lesser value before a fire.

Careful documentation of the remaining contents and debris may help establish a fraudulent insurance claim, even when the fire’s cause cannot be determined.

Determining that contents were removed or replaced requires verification that the items were present before the fire. Verification may be obtained through:

• Corroborated witness statements

• Photographs

• Inventory records

• Sales receipts

It may be necessary to document all contents of the occupancy, not only the contents located near the area of origin.

Personal or irreplaceable items may sometimes be removed before an incendiary fire, including:

• Jewelry

• Photographs

• Pets

• Tax records

• Business records

• Firearms

Items and contents that may be replaced can include:

If the building’s contents are abnormal for the particular occupancy, this could indicate that further investigation is necessary.

Blocked or Obstructed Entry

A fire-setter may place obstructions intended to hinder or delay firefighting operations, allowing the fire additional time to grow.

Any unusual obstruction that could prevent access by fire apparatus should be noted and evaluated.

Obstructions may include:

• Fallen trees

• Barricades

• Larger obstructions capable of blocking emergency-vehicle access

• Obstructed doors

• Obstructed windows

Tip: Document every step of the investigation photographically. You can never take too many photographs. The one photograph you will need will invariably be the one you did not take.

Sabotage

Sabotage means intentional damage or destruction.

Fire-setters often attempt to establish conditions that will produce rapid and complete destruction of a building and its contents. To accomplish this, a fire-setter may sabotage fire-protection systems so that notification to occupants and the fire department is delayed.

Figure 15-12 – Fire-setters may sabotage fire protection systems to delay notification of the fire department

The figure identifies delayed notification as a possible purpose of sabotaging a fire-protection system.

Certain indicators may assist an investigator in developing:

• An ignition hypothesis

• Questions for witnesses

• Areas for further investigation

These indicators are generally not related directly to determining the fire’s cause. Instead, they may indicate that someone had prior knowledge of the fire.

Remote Locations with Blocked or Obstructed View

A fire-setter may start a fire in a remote location or in a location obscured from public view.

Of particular importance are actions taken shortly before the fire to obstruct the view, including:

• Newly covered windows

• Newly painted windows

• Furniture placed in front of exterior openings

These observations may provide information useful for:

• Establishing timelines

• Questioning witnesses

Accidental fires can also begin in remote locations. No cause-determination conclusion should be based solely on the location of origin.

Fires Near Service Equipment and Appliances

A fire-setter may start a fire near an appliance to make the fire appear accidental, hoping investigators will assume that the appliance was the ignition source.

Each appliance must be evaluated carefully to determine whether it was actually the ignition source.

Investigators must consider spoliation issues before performing any destructive evaluation.

Tip: Always strive to conduct investigations systematically. Establish a normal routine for each fire so that all investigations are eventually performed automatically in the same manner, consistent with NFPA 921, Guide for Fire and Explosion Investigations, Sections 4.2 and 4.3.

Part 7 – Damage to Fire-Protection Features and Other Evidentiary Factors

Damage to Fire-Resistive Assemblies

Fire-resistive assemblies divide a structure into compartments, helping confine fire and smoke and prevent their spread to other parts of the structure.

Open doors are the most common route through which fire travels within a structure. Open stairwell doors can have an even greater effect on fire spread.

A fire-setter may:

• Penetrate fire-resistive walls, floors, or ceilings

• Prop doors open to facilitate the movement of fire and smoke

However, penetrations in these assemblies may also result from:

• Firefighting activities

• Poor construction

Occupants may also prop doors open to improve access or ventilation.

Because these other explanations are possible, it is important to conduct a thorough investigation and not assume sabotage.

Damage to Fire-Protection Systems

An occupancy may contain many types of fire-detection and suppression systems. When these systems operate normally, they should help detect or suppress a fire before it causes significant damage.

Some systems may also be designed to notify the fire department when a fire occurs.

Examples include:

• Smoke-detection systems

• Fire-detection systems

• Flame-detection systems

• Security cameras

• Sprinklers

• Standpipes

• Extinguishing systems

If a fire-suppression or fire-detection system has failed, inspect the system for signs that may identify the cause of the failure, including:

• Improper installation

• Tampering

• Lack of maintenance

• System shutdown

• Equipment failure

• Structural-assembly failure

It is also important to determine whether these conditions existed before the fire. Inspection and maintenance records could provide valuable information concerning the system’s prefire condition.

Methods of disabling fire-protection systems include:

• Removing or covering smoke detectors

• Obstructing sprinklers

• Shutting off control valves

• Damaging threads on standpipes, hose connections, and fire hydrants

• Placing debris in pipe splitters and fire hydrants

• Disconnecting alarm bells or sirens

• Starting multiple fires to overload the suppression system

An investigator should always examine fire-protection systems to determine whether tampering or disabling occurred.

The investigator should also check alarm-monitoring facilities to determine when trouble or alarm signals were received. This information may help define the fire’s timeline.

Tip: Some fire-setter actions can create additional safety concerns for firefighters and investigators who remain alive. For example, a fire-setter may intentionally weaken supporting structures in an attempt to delay firefighting operations and obscure evidence. Investigators must remain alert to the potential for building sabotage and take the necessary safety precautions.

Damage to Buildings

A fire-setter may intentionally damage a building:

1. To hinder firefighters’ ability to fight the fire effectively

2. To provide routes for the fire to spread beyond its area or areas of origin

Examples could include:

• Cutting openings in floors through which firefighters could fall

• Breaching other fire-rated assemblies, such as walls or doors, to permit fire spread

• Jamming or barricading doors and windows to make firefighter entry difficult

• Sabotaging fire-rated doors, fire dampers, and similar components so that they remain open during a fire and do not close automatically

Exercise due care during the fire-scene examination when determining whether a fire-protection system or component failed because of an intentional act rather than inadequate maintenance.

For example, occupants sometimes prop open or disable fire- and smoke-rated doors as a normal practice.

Other possible reasons for failure should also be examined, including:

• Manufacturing defects

• Installation defects

Opening Windows and Doors

To provide ventilation to a fire, a fire-setter may open exterior windows or doors that would not normally be open, such as during cold weather.

The objective could be to create artificial routes of fire propagation, allowing the fire to spread outside the compartment containing the area of origin.

The investigator should determine:

• Whether occupants normally propped the doors open

• Whether the action may have been taken to spread the fire

Wind direction may also have been a factor that the fire-setter attempted to exploit to spread the fire.

Tip: Examine all available court, real-estate, business, maintenance, code-enforcement, and other records and documents concerning the vehicle, property, structure, or person under investigation. This may help establish a motive for the fire.

Other Evidentiary Factors

Other evidentiary factors include indicators that can be analyzed after a fire has been determined to be incendiary. These indicators may help develop a potential profile of the suspect.

Serial Crimes

Patterns in fire-setting are important when attempting to develop a suspect profile and eventually identify the suspect.

The terms serial fire-setter and serial arsonist identify individuals or groups involved in three or more fire-setting incidents.

When investigating a series of fires, analyze which fires may be attributable to one suspect or group by considering:

1. Geographic location or cluster: Fire-setters tend to act within the same geographic location or neighborhood.

2. Temporal frequency: A serial arsonist may select the same time period or day of the week.

3. Materials and methods: Repetitive fire-setting behavior may occur in the same geographic location and use similar fire-setting materials and methods.

A perpetrator can sometimes be identified by analyzing crime attributes that suggest a connection to one individual.

Modus Operandi

Modus operandi (MO) is the offender’s method of operation and applies predominantly to serial arsonists.

The offender’s actions during the commission of a crime form the MO. The offender develops and uses the MO over time because it works, but the MO also continually evolves.

An MO is learned behavior and may be modified as the offender becomes more sophisticated and confident.

Personation

Personation, also called the signature, is unusual behavior by an offender that goes beyond what is necessary to commit the crime.

The offender may add personal meaning or ritualistic behavior to the crime. Common features in this behavior can be used to help identify the offender.

Staging

Staging is the purposeful alteration of a crime scene before police arrive.

Two reasons are generally associated with staging:

• Redirecting the investigation away from the most logical suspect

• Protecting a victim or the victim’s family from a gruesome or demeaning scene by changing the position of the victim or body

Timed Opportunity

Fire-setters sometimes take advantage of conditions or circumstances that increase the likelihood of successfully destroying property.

A timed opportunity can also improve the fire-setter’s chance of avoiding apprehension.

Examples include:

• Natural conditions such as hurricanes, floods, snowstorms, or high winds

• Civil unrest

• Fire department unavailability because of:

  • Response to another alarm, potentially called in by the suspect

  • Parades

  • Other calls

Fire-setters may take advantage of conditions or circumstances that increase the likelihood of successfully destroying property. A timed opportunity may also reduce the likelihood that the fire-setter will be apprehended.

Examples include:

• Natural conditions such as hurricanes, floods, snowstorms, or high winds

• Civil unrest

• Fire department unavailability because of:

  • Response to another alarm, potentially called in by the suspect

  • Parades

  • Other calls

Part 8 – Motives for Fire-Setting Behavior

Motive

Motive is the inner drive or impulse that is the cause, reason, or incentive inducing or prompting a particular behavior.

Motive indicators found during a fire investigation can be used to help identify potential suspects, but they should not be used to determine or classify the fire’s cause.

Intent and motive are different:

• Intent is generally necessary to prove a crime and concerns a person’s state of mind when acting or failing to act.

• Motive is the reason an individual or group may do something and is generally not a required element of a crime.

The classifications in this chapter are based on Douglas et al., Crime Classification Manual (CCM), 2013.

The CCM can help investigators gather as much information as possible by identifying essential analytical factors used to classify the motive behind:

• Murder

• Arson

• Sexual offenses

Behaviors identified in the CCM may indicate a possible motive and lead investigators to possible suspects. These behaviors apply whether the fire is:

• A one-time occurrence

• Part of a series of fire-setting incidents

Classifications of Repetitive Fire-Setting Behavior

Motive Classifications

The National Center for the Analysis of Violent Crime (NCAVC) identifies six motive classifications as the most effective for identifying offender characteristics associated with fire-setting behavior:

1. Vandalism

2. Excitement

3. Revenge

4. Crime concealment

5. Profit

6. Extremism

Vandalism

Vandalism is mischievous or malicious fire-setting that damages property.

Common targets include:

• Educational facilities

• Abandoned structures

• Trash

• Grass

Vandalism is divided into two categories.

Willful and Malicious Mischief

These are incendiary fires with no apparent motive or fires that appear to have been set randomly.

They are often attributed to:

• Juveniles

• Adolescents

Peer or Group Pressure

Recognition or pressure from peers can inspire vandalism and is a predominant motive among juveniles.

Juveniles are often influenced more strongly by the people accompanying them than by the potential consequences of their actions.

Excitement

Some people set fires because they seek excitement. This type of perpetrator generally does not intend to hurt anyone in the fire, but unplanned injuries and deaths can occur.

Excitement has four subcategories.

Thrill Seeking

Thrill-seeking offenders experience feelings of excitement and power and are often repetitive fire-setters.

A psychological need or desire drives them to set these fires.

Attention Seeking

Attention-seeking fire-setters need to feel important.

Recognition

Recognition-seeking offenders are sometimes called vanity fire-setters or hero fire-setters.

Possible offenders may include:

• Paid firefighters

• Volunteer firefighters

• Security guards

A desire for recognition, praise, or reward can drive their behavior.

If successful, these offenders will most likely repeat the offense multiple times. They are often still present at the scene and provide extensive details concerning:

• The fire’s location

• How to reach the location

They are usually very forthcoming with information and helpful to firefighters and police.

Sexual Gratification or Perversion

Although considered rare, documented cases exist in which offenders set fires as a means of sexual release.

They may remain in the area so they can observe the fire, although they may remain hidden from view.

Revenge

An offender may set a fire to seek revenge for a real or imagined injustice committed against:

• The offender

• Someone the offender cares about

These fires are sometimes premeditated and well planned. They are usually one-time events, although serial arsonists sometimes set multiple revenge fires.

Revenge includes four subcategories.

Personal Retaliation

A particular event commonly triggers a retaliatory response, such as:

• A fight

• An argument

• A feeling that the offender or someone close to the offender has been taken advantage of

Common targets include the victim’s:

• Home

• Personal possessions

• Vehicle

Societal Retaliation

A serial offender may belong to this subcategory.

The offender may experience recurring feelings of:

• Loneliness

• Rejection

• Persecution

• Abuse

• Inadequacy

These feelings may drive the person to set fires. As the feelings recur, the offender may continue setting fires as a release and for a sense of gratification.

Investigators should look for a similar MO in these fires.

Institutional Retaliation

This motive usually involves a person who holds a grudge against an institution.

The offender may be a former:

• Employee

• Customer

• Patient

• Student

Common targets include:

• Religious institutions

• Medical institutions

• Government institutions

• Educational institutions

• Corporations

Group Retaliation

Targets may involve:

• Fraternal groups

• Religious groups

• Racial groups

• Other groups, including gangs

Evidence at these scenes may include:

• Graffiti

• Symbols or markings

• Other vandalism

Crime Concealment

In crime concealment, arson is generally a secondary or collateral criminal activity. Its purpose is to conceal the initial criminal activity that occurred.

Murder Concealment

When a murder has been committed, a fire is usually set to:

• Conceal the fact that the death occurred before the fire

• Destroy forensic evidence that could identify the victim

A fire may also be set to destroy evidence that could connect the offender to the crime.

Burglary Concealment

These fires are usually set to:

• Conceal the fact that a burglary occurred

• Destroy evidence that could identify the burglar or fire-setter

Destruction of Records or Documents

The general targets are records or documents associated with a:

• Business

• Institution

• Corporation

Fires may be started:

• In file cabinets, which are often found with drawers left open

• In folders containing files

• In other documents

Investigators should consider employees or owners of the location as potential suspects.

Profit

Fires set for profit are intended to produce material or monetary gain. The monetary issue may be directly or indirectly connected to the fire.

Profit-motivated arson is a commercial crime involving the least amount of passion of any arson motive.

Direct gain may come from:

• Insurance fraud

• Elimination or intimidation of business competition

• Extortion

• Removal of unwanted structures to increase property values

• Escaping financial obligations

Additional subcategories include setting fires to:

• Liquidate property

• Dissolve a business

• Conceal a loss

• Liquidate inventory

Other categories include:

• Employment

• Parcel or property clearance

• Competition

Investigating Financial Motives

Sources that can help uncover potential financial motives include:

• Bank records

• Insurance policies

• Code-enforcement complaints or sanctions

• Fire-inspection complaints or sanctions

• National Insurance Crime Bureau records

• Tax records

• Other financial records

Potential indicators include:

• Financial stress

• A history of code violations

• Fires at additional properties owned by the same individual or group

• Over-insured property

Other circumstances that can establish or support a financial motive include:

• Liens

• Attachments

• Unpaid taxes

• Mortgage payments in arrears

• Real estate offered for sale

• Poor business location or competition

• Economic decline

• Outdated or overstocked products

• Loss of jobs

• Over-insurance

• Recent policy changes intended to inflate property values

The investigator should also examine past insurance histories to determine whether the claimant previously submitted claims for fires involving other buildings or vehicles.

Extremism

Extremism becomes a motive when the fire-setter intends to advance a:

• Political cause

• Social cause

• Religious cause

These fires may be set by individuals or groups.

Fire-setters in this category generally demonstrate a high degree of organization, reflected in their use of more elaborate ignition or incendiary devices.

Extremism includes terrorism and riot or civil disturbance.

Terrorism

Targets selected by terrorists are rarely random. They are generally chosen because of a particular significance that will create the greatest impact for the message the terrorists want to deliver.

Common objectives may be:

• Political

• Economic

Political targets include:

• Government offices

• Newspapers

• Universities

• Political-party headquarters

• Animal-research facilities

• Abortion clinics

• Military installations

• Law-enforcement installations

Economic targets may include:

• Business offices

• Distribution facilities

• Banks

• Financial institutions

• Companies believed to have an adverse effect on the economy

Fire, explosions, and other weapons may be used in these assaults.

Riot or Civil Disturbance

Fires occurring during riots or civil disturbances are usually intentional and are generally accompanied by:

• Looting

• Vandalism

Investigators need to determine whether the fire was:

• An act committed by the rioting crowd

• Set by a building owner seeking financial benefit by having the fire attributed to the ongoing riot

The National Center for the Analysis of Violent Crime (NCAVC) identifies six motive classifications as the most effective for identifying offender characteristics associated with fire-setting behavior:

1. Vandalism

2. Excitement

3. Revenge

4. Crime concealment

5. Profit

6. Extremism

Vandalism

Vandalism is mischievous or malicious fire-setting that damages property.

Common targets include:

• Educational facilities

• Abandoned structures

• Trash

• Grass

Vandalism is divided into two categories:

Willful and Malicious Mischief

These incendiary fires:

• Have no apparent motive

• Appear to have been set randomly

• Are often attributed to juveniles or adolescents

Peer or Group Pressure

Recognition or pressure from peers may inspire vandalism and is a predominant motive among juveniles.

Juveniles are often influenced more by the people accompanying them than by the potential consequences of their actions.

Excitement

Some offenders set fires because they seek excitement. These offenders generally do not intend to harm anyone, but unplanned injuries and deaths may occur.

Excitement has four subclassifications.

Thrill Seeking

Thrill-seeking offenders:

• Experience feelings of excitement and power

• Are often repetitive fire-setters

• Are driven by a psychological need or desire to set fires

Attention Seeking

Fire-setters in this classification have a need to feel important.

Recognition

These offenders are sometimes called vanity fire-setters or hero fire-setters.

Possible offenders in this classification include:

• Paid firefighters

• Volunteer firefighters

• Security guards

Their behavior may be driven by a need for:

• Recognition

• Praise

• Reward

If they are successful, they will most likely repeat the offense multiple times.

These offenders may:

• Remain at the scene

• Provide extensive details about the fire’s location

• Explain how to reach the location

• Be very forthcoming with information

• Appear helpful to firefighters and police

Sexual Gratification or Perversion

Although considered rare, documented cases exist in which offenders set fires as a means of sexual release.

These offenders may remain in the area to observe the fire, although they may remain hidden from view.

Revenge

An offender may set a fire in revenge for a real or imagined injustice committed against:

• The offender

• Someone the offender cares about

These fires may be premeditated and carefully planned. They are usually one-time events, although serial arsonists may commit them repeatedly.

Revenge has four subcategories.

Personal Retaliation

An event may trigger a retaliatory response, such as:

• A fight

• An argument

• A feeling of having been taken advantage of

The event may involve the offender or someone close to the offender.

Common targets include the victim’s:

• Home

• Personal possessions

• Vehicle

Societal Retaliation

Serial offenders may fall within this subclassification.

The perpetrator may experience feelings of:

• Loneliness

• Rejection

• Persecution

• Abuse

• Inadequacy

As these feelings recur, the offender may continue setting fires for release and gratification. Investigators should look for a similar MO among the fires.

Institutional Retaliation

This motive commonly arises when an individual holds a grudge against an institution.

The offender may be a former:

• Employee

• Customer

• Patient

• Student

Common targets include:

• Religious institutions

• Medical institutions

• Governmental institutions

• Educational institutions

• Corporations

Group Retaliation

Targets may include:

• Fraternal groups

• Religious groups

• Racial groups

• Other groups, including gangs

Evidence at these scenes may include:

• Graffiti

• Symbols or markings

• Other vandalism

Crime Concealment

In crime concealment, arson is generally a secondary or collateral criminal activity. Its purpose is to conceal an earlier criminal act.

Crime concealment has three subcategories.

Murder Concealment

After a murder, a fire may be set to:

• Conceal that the death occurred before the fire

• Destroy forensic evidence capable of identifying the victim

• Destroy evidence connecting the offender to the crime

Burglary Concealment

A fire may be set to:

• Conceal that a burglary occurred

• Destroy evidence capable of identifying the burglar/fire-setter

Destruction of Records or Documents

Targets generally include records or documents belonging to a:

• Business

• Institution

• Corporation

Fires may be started:

• Inside file cabinets, which may be found with their drawers open

• In folders containing files or other documents

Investigators should consider employees or owners of the location as potential suspects.

Profit

Fires set for profit are intended to produce material or monetary gain. The financial benefit may be directly or indirectly connected to the fire.

Profit-motivated arson is a commercial crime involving the least amount of passion among the listed arson motives.

Direct gain may result from:

• Insurance fraud

• Elimination or intimidation of business competition

• Extortion

• Removal of unwanted structures to increase property values

• Escape from financial obligations

Additional subclassifications include fire-setting intended to:

• Liquidate property

• Dissolve a business

• Conceal a loss

• Liquidate inventory

Other categories include:

• Employment

• Parcel or property clearance

• Competition

Investigators can use several sources to identify possible financial motives, including:

• Bank records

• Insurance policies

• Code-enforcement complaints or sanctions

• Fire-inspection complaints or sanctions

• National Insurance Crime Bureau records

• Tax records

Possible indicators include:

• Financial stress

• History of code violations

• Fires at additional properties owned by the same individual or group

• Over-insured property

Other circumstances that may establish or support a financial motive include:

• Liens

• Attachments

• Unpaid taxes

• Mortgage payments in arrears

• Real estate offered for sale

• Poor business location

• Business competition

• Economic decline

• Outdated or overstocked products

• Loss of jobs

• Over-insurance

• Recent policy changes intended to inflate property values

Investigators should examine the claimant’s insurance history to determine whether previous fire claims involved other buildings or vehicles.

Extremism

Extremism becomes a motive when a fire-setter intends to advance a:

• Political cause

• Social cause

• Religious cause

These fires may be set by individuals or groups. Fire-setters in this category generally demonstrate substantial organization through the use of more elaborate ignition or incendiary devices.

Extremism includes terrorism and riot/civil disturbance.

Terrorism

Targets selected by terrorists are rarely random. They are usually selected for a particular significance that produces the greatest impact for the intended message.

The objective may have political or economic significance.

Political targets may include:

• Government offices

• Newspapers

• Universities

• Political-party headquarters

• Animal-research facilities

• Abortion clinics

• Military installations

• Law-enforcement installations

Economic targets may include:

• Business offices

• Distribution facilities

• Banks

• Financial institutions

• Companies believed to have an adverse effect on the economy

Fire, explosives, and other weapons may be used in these assaults.

Riot/Civil Disturbance

Fires occurring during riots or civil disturbances are generally:

• Intentional

• Accompanied by looting

• Accompanied by vandalism

Investigators must determine whether the fire was set by:

• A rioting crowd

• Building owners seeking financial benefit by having the fire attributed to the riots

Part 9 – Human Behavior and Fire and Examples of Fire-Fatality Events

Human Behavior and Fire

A fire’s origin, development, and consequences are all related—directly or indirectly—to the actions or omissions of human beings.

Understanding the behavior of witnesses and occupants is integral to the fire-scene examination. By understanding why occupants or witnesses behaved in a particular way, the investigator can better evaluate:

• Fire development

• Fire cause

• Evidence found at the scene

Research indicates that an individual’s or group’s behavior before, during, and after a fire can provide valuable information for the investigator.

Factors affecting behavior include:

• Characteristics of the individual

• Characteristics of the group or population to which the individual belongs

• Characteristics of the physical setting where the fire occurs

• Characteristics of the fire itself

Characteristics of the Individual

Physical limitations can adversely affect a person’s ability to take appropriate action before and during a fire, including:

• Age as it relates to mobility

• Physical disabilities

• Injuries

• Medical conditions

• Chemical impairment

The very young and very old are most susceptible to these limitations.

Cognitive limitations can hinder a person’s ability to recognize and respond appropriately to a fire or explosion.

Factors that can limit cognitive ability include:

• Age as it relates to mental comprehension, such as a child hiding instead of escaping

• Level of education

• Legal or illegal drug use

• Developmental disabilities

• Mental illness

• Inhalation of smoke and toxic gases

Greater familiarity with a setting can make escape during a fire more likely, although physical and cognitive limitations can reduce the advantages of that familiarity.

In large or unfamiliar structures, people tend to leave by the same route they used to enter. An emergency causes the mind to focus on known, familiar exits and limits a person’s ability to seek or consider alternative exits.

Characteristics of the Group or Population

The size of a person’s group can influence that person’s response to a threat or reported threat.

The likelihood of a delayed or inappropriate reaction increases as group size increases. Research has shown that people in groups may delay responding to sensory cues until other members of the group acknowledge and react to those cues.

When a group has a formal structure with defined and recognized leaders, it tends to respond more quickly and in a more orderly way. However, the response is not always appropriate.

Examples of formally structured groups include populations in:

• Schools

• Hospitals

• Nursing homes

• Religious facilities

The permanence of a group, or the degree of familiarity among its members, also affects response times.

Members of established groups whose members know one another well—such as families, sports teams, or clubs—react and notify one another more quickly than:

• Newly formed groups

• Groups whose members are unfamiliar with one another

Group roles and norms may also influence the response to a threat, including roles associated with:

• Gender

• Social class

• Occupation

• Education

For example, studies of fire or explosion events have shown that:

• Males are more likely to participate in activities intended to suppress or defuse the threat.

• Females are more likely to report the threat.

Characteristics of the Physical Setting

The characteristics of a burning structure affect the responses of the people inside it.

Occupants unfamiliar with the building often experience increased stress, which can produce unpredictable behavior. They often attempt to leave through the door they used to enter, even when doing so moves them toward the threat.

It is important that exits be clearly marked.

The number of available exits also significantly affects occupant behavior. Too few exit routes, or exits that are blocked or restricted, expose occupants to additional danger.

Fire-alarm systems can help occupants recognize a threat.

Figure 15-13 – A fire alarm system can include lights and horns to notify occupants

The figure identifies lights and horns as possible components of a fire-alarm system used to notify occupants.

Research has shown that voice or directive messages may produce better responses than strobes and horns alone.

If a building has experienced numerous false alarms, occupants tend to delay their response until the actual fire emergency is confirmed, increasing the danger that they will become trapped.

Fire-suppression systems provide greater time for occupants to react to a threat. However, occupants may overestimate the amount of additional time available.

Some systems, once discharged, can reduce visibility and affect occupants’ ability to escape.

Figure 15-14 – Sprinklers indicate the presence of a fire suppression system

The figure identifies sprinklers as an indication that a fire-suppression system is present.

Characteristics of the Fire

An individual’s or group’s response to a threat is influenced by how that individual or group perceives the hazard.

Most individuals do not understand:

• The threat presented by flames

• The ability of fire to grow exponentially

• The ability of fire to release toxic products into the air

As a result, they may disregard small flames as a source of danger.

Many people lack knowledge concerning the toxic and incapacitating effects of smoke or believe that lighter-colored smoke is less dangerous than darker smoke.

Many people also do not understand that fire consumes oxygen and may reduce the available oxygen within an enclosed space.

When oxygen concentration falls below 15 percent:

• Motor skills become impaired.

• Mental skills become impaired.

• The condition can ultimately become fatal.

Behavior displayed by victims under these conditions may appear inappropriate but may result from confusion caused by:

• Inhalation of toxic gases

• Oxygen deprivation

A person may be impaired by more than one factor. For example, a person may already be impaired by alcohol and then experience additional impairment from the effects of fire or products of combustion.

Examples of Human Behavior Contributing to Fire Fatalities

Many catastrophic fires throughout history have resulted in significant loss of life.

Although many factors generally influence the scale of these incidents—including criminal activity, inappropriate use of heat-producing devices, and uncorrected code violations—the occupants’ response also plays an important role.

The Station Nightclub Fire

On February 20, 2003, the band Great White was scheduled to perform before a packed nightclub in West Warwick, Rhode Island.

At approximately 11:07 p.m., the band began its opening song, “Desert Moon.” As part of the performance, three pyrotechnic gerbs produced fountains of sparks against the walls of the stage area.

The foam material on the stage walls ignited, producing a rapidly developing fire that killed 100 people.

A television news crew was filming a segment about nightclub safety that night and captured the event as it became one of the deadliest fires in United States history.

The recording documented both fire dynamics and human behavior:

• Spectators and band members initially failed to recognize that the wall covering had ignited or understand the danger.

• Patrons first recognized the fire approximately 24 seconds after ignition.

• Most patrons began evacuating approximately 30 seconds after ignition, when the band stopped playing.

• Some patrons had been consuming alcoholic beverages.

• Most occupants attempted to leave through the familiar main entrance even though three other exits were available.

The mass movement through the main doors caused severe congestion. The doorway quickly became filled with a tangled mass of victims.

The outcome included:

• 96 deaths at the fire scene

• 4 additional deaths in local hospitals

• 230 injuries

• Only 132 people escaping without injury

MGM Grand Hotel Casino Fire

On November 21, 1980, a fire began in a vacant restaurant within the MGM Grand Hotel and Casino in Las Vegas, Nevada.

The fire resulted in:

• 85 deaths

• 650 injuries

The fire began in a wall soffit in an area where a sprinkler exemption applied, contributing to its rapid development.

Fire spread was assisted by:

• Wallpaper

• Polyvinyl chloride (PVC) piping

• Plastic mirrors

The fire eventually traveled through the lobby and produced a fireball from the front entrance.

Most fatalities resulted from toxic fumes circulated through the hotel’s HVAC system. Many upper-floor victims died from:

• Smoke inhalation

• Carbon-monoxide poisoning

Many occupants entered stairwells that served as chimneys, carrying toxic smoke and gases to the building’s upper areas. Once inside, occupants became trapped because doors behind them locked, leaving exits only at:

• The ground floor

• The roof

An NFPA review found that hotel occupants did not panic. Many took rational actions to survive, including:

• Warning other occupants

• Placing towels at the bases of doors

• Covering their faces with wet cloths

Several months later, on February 10, 1981, an arson fire occurred at the Las Vegas Hilton.

Using lessons from the MGM Grand investigation, firefighters used local television networks to instruct occupants to remain in their rooms and stay out of hallways and stairwells.

Although 8 people died, the firefighters’ actions are believed to have prevented a much greater loss of life.

Kiss Nightclub Fire

On January 27, 2013, a fire caused by the inappropriate use of an outdoor pyrotechnic device inside the Kiss Nightclub in Santa Maria, Rio Grande do Sul, Brazil, resulted in:

• 242 deaths

• 168 injuries

Similar to The Station Nightclub fire, a pyrotechnic device ignited acoustic foam lining the ceiling above the stage.

After the fire began:

• A stampede occurred as people attempted to escape.

• The building lacked lighted exit signs.

• The building lacked emergency exits.

• Most victims died from smoke inhalation.

• Many victims died after attempting to hide in bathrooms or mistaking bathroom doors for exits.

• More than 150 people were injured by the rapidly accumulating smoke inside the nightclub.

Other contributing factors included:

• False information concerning the number of emergency exits during the permit-issuance process

• Missing or false information concerning functional fire extinguishers

After the incident, Brazilian authorities inspected similar nightclubs for safety concerns. These inspections resulted in the closure of 58 facilities.

On January 27, 2013, an outdoor pyrotechnic device was used improperly inside the Kiss Nightclub in Santa Maria, Rio Grande do Sul, Brazil.

The incident caused:

• 242 deaths

• 168 injuries

As in the Station Nightclub fire, the pyrotechnic device ignited acoustic foam lining the ceiling above the stage.

After the fire began, a stampede developed as occupants attempted to escape. Their efforts were severely hindered by:

• A lack of exit signs

• A lack of emergency exits

Most victims died from smoke inhalation.

Many people died because they:

• Attempted to hide in bathrooms

• Mistook bathroom doors for exits

More than 150 people were injured by:

• The crush at the front door

• Rapidly accumulating smoke inside the nightclub

Other factors contributing to the incident’s severity included:

• False information about the number of emergency exits during the permit-issuance process

• Missing or false information concerning functioning fire extinguishers

After the incident, Brazilian authorities inspected similar nightclubs and closed 58 facilities because of safety concerns.

Part 10 – Factors Related to Fire Initiation, Children and Fire, and Recognition and Response

Factors Related to Fire Initiation

Fire and explosion incidents frequently result from an act or omission by one or more people before or during the fire.

Human actions can encourage or prevent fire spread. The investigator should assess actions that may include:

• Opening or closing doors

• Operating fire-protection systems

• Rescue efforts

Common human actions associated with fire initiation and spread include:

• Improper maintenance and operation of equipment or appliances

• Careless housekeeping

• Failure to follow product labels, instructions, warnings, and recalls

• Violations of fire-safety codes and standards

Improper Maintenance and Operation

During the service life of most equipment, the equipment is subject to a prescribed maintenance and cleaning schedule. This schedule is usually supplied by the manufacturer and should be followed to prevent malfunction.

Required maintenance becomes critically important when equipment is capable of:

• Producing an explosion

• Starting a fire

Operating procedures for equipment and appliances are designed to provide safe operation.

If maintenance or operating procedures are neglected or performed incorrectly, the lapse can result in a fire or explosion.

Examine maintenance records and operating instructions carefully to determine whether the proper procedures were followed.

Housekeeping

Household equipment capable of initiating a fire or explosion generally includes instructions establishing recommended clearance distances between the equipment and combustible materials.

Examples of hazards include:

• Portable heaters or ignitable lights that are not kept the specified distance from other materials

• Carelessly discarded smoking products, such as cigarettes or cigars

• Grease accumulation in cooking areas

• Improperly stored cleaning solutions

Note any housekeeping irregularities that may have contributed to the fire or explosion.

Manufacturers’ Product Labels, Instructions, and Warnings

Labels, instructions, and warnings are placed on products to prevent misuse or abuse.

• Manufacturers’ labels inform users about a product’s capabilities.

• Instructions provide users with relevant information about how the product is intended to be used.

• Warnings alert users to dangers that may arise when the product is not used as intended and remind users of the product’s hazards.

A proper warning contains four essential elements:

1. An alert word signaling danger

2. A statement describing the danger

3. A statement explaining how to avoid the danger

4. An explanation of the consequences of the danger

Figure 15-15 – The investigator should read any labels, instructions, or warnings on products

The figure emphasizes that investigators should examine product labels, instructions, and warnings.

According to ANSI Z535.4, Product Safety Signs and Labels:

• CAUTION: Indicates a potentially hazardous situation that, if not avoided, may result in minor or moderate injury.

• WARNING: Indicates a potentially hazardous situation that, if not avoided, could result in death or serious injury.

• DANGER: Indicates an imminently hazardous situation that, if not avoided, will result in death or serious injury.

Government Standards on Labels, Instructions, and Warnings

Like many manufacturers, the government establishes standards, guidelines, and regulations addressing:

• Safety warnings

• Safe product design

Manufacturers’ warnings are common and helpful when they accompany a product, while government standards are important in defining parameters for a particular product or substance.

Figure 15-16 – Standards on labels, instructions, and warnings

The figure identifies the following standards, codes, regulations, and industry guidance:

1. ANSI Standards on Labeling

2. UL Standard on Labeling

• UL 969, Standard for Marking and Labeling Systems

3. United States Federal Codes and Regulations

4. Industry Standard

• FMC Product Safety Sign and Label System Manual

Recall Notices

A recall notice is a method of notifying consumers about a product defect discovered after the product was released for consumer use.

Most recalls result from identifying a dangerous condition that could arise even when the product is used as intended.

If a person disregards a recall notice and continues using the product, the outcome can be:

• A fire

• An explosion

• Another catastrophic event

Recall notices can be located through the Consumer Product Safety Commission.

Tip: Government and industry have developed accepted guidelines and standards for product labels, warnings, and instructions. Institutions addressing these requirements include:

• American National Standards Institute (ANSI)

• Underwriters Laboratories

• FM Global

• United States codes and regulations within the Code of Federal Regulations (CFR)

Violations of Fire-Safety Codes and Standards

Noncompliance with fire-safety codes and standards can result in a fire or explosion. The noncompliance may be:

• Deliberate

• Unintentional

During an origin-and-cause investigation, it is frequently difficult to determine whether the incident involved:

• Deliberate product misuse or abuse

• Carelessness

• Another contributing factor

Examine:

• Training records

• Maintenance records

• Other documentation

Look for a pattern that may indicate the incident’s potential cause.

Check with the local fire-prevention bureau to determine whether the business had been cited for fire-code violations.

Children and Fire

Children’s curiosity about fire and experimentation through fire play are considered relatively normal childhood activities.

Children may also be motivated to set fires by:

• Frustration

• Anger

• Revenge

• A need for attention

The location and motive for setting fires vary with the child’s age and developmental stage.

Preschool-Age Children

Preschool-age children understand the world primarily as it affects them, or egocentrically. They may not understand cause and effect, such as how a small fire can grow into a large fire, unless they have personally experienced the event.

Preschool-age children:

• Are motivated by pleasure

• Typically set fires from curiosity

Early Elementary School-Age Children

Early elementary school-age children may be interested in the processes of fire, such as the consumption of materials.

They tend to:

• Observe adults

• Imitate adults

They still have difficulty understanding cause and effect.

Children Approximately 8 to 12 Years Old

Children between approximately 8 and 12 years old understand cause and effect.

Emotional and crisis fire-setting behavior may occur in this age group because the child cannot cope with:

• Trauma

• Change

Fires may also result when a child:

• Assumes too much responsibility

• Allows a fire to grow without requesting help because the child does not want to appear incompetent

Adolescent Children

Adolescents may set delinquent fires.

Their motivations may include:

• A need for acceptance from peers

• A desire to test limits

• Boredom

Although adolescents have more responsibility and freedom than younger children, they may be unwilling to:

• Think a situation through

• Accept responsibility for negative outcomes

Tip: Fire-prevention and fire-investigation personnel use the terms fire-setters and arsonists when discussing youths involved in starting fires. However, these terms should be avoided when discussing youth-involved fires with:

• The youths involved

• Their families

• Members of the public

Investigation of Fires Involving Youths

The fire investigator plays a very important role when youth involvement is suspected.

Information and evidence obtained or observed at the fire scene may be critical in allowing the investigation team and other specialists to identify and address adequately the issues involving a youth.

The investigator should know the legal rules that apply in the jurisdiction, including:

• The age at which a youth can be charged within the criminal-law system

• Whether the juvenile or adult system would be involved

• The roles of parents and guardians

The investigator should note:

• Where the fire began

• Whether the fire involved planning

• Whether lighters and fuels were easily accessible

With younger children, the investigator may find evidence of a fire in which the child:

• Sleeps

• Plays

• Used readily accessible fuel and ignition sources

• Potentially involved toys, bedding, or clothing

Older children may set fires in less accessible public areas. These fires may involve:

• Lighters

• Matches

• Fireworks

• Other devices

• Vegetation

• Ignitable liquids

Recognition and Response to Fires

In a fire situation, an occupant’s ability to recognize danger is critical to survival.

The occupant must be able to respond appropriately to the perceived and actual dangers associated with the event.

Sensory perception can be affected by:

• Physical condition

• Mental condition

• Alcohol consumption

• Drug consumption

An occupant’s actions are based on four sensory factors:

When an occupant identifies a threat such as a fire or explosion, that person must decide how to respond.

Possible choices include:

• Ignoring the problem

• Investigating the problem

• Fighting the fire

• Signaling an alarm

• Rescuing or assisting others

• Fleeing the fire

• Remaining in place

• Reentering the structure after successfully escaping

The final decision is influenced by the person’s state of mind.

The ability to escape is affected by:

• How easily escape routes can be identified

• Distance to the escape routes

• Fire conditions, including smoke, heat, or flames

• Dead-end corridors

• Obstacles or people blocking the escape route

• Physical disabilities

• Physical impairments

Interviews with survivors can provide information useful in determining how people behaved before and during a fire or explosion.

Figure 15-17 – Interviews can lead investigators to important information

Survivor interviews can help establish:

• Prefire conditions

• Fire and smoke development

• Fuel packages and their locations and orientations

• Victims’ activities before, during, and after discovering the fire or explosion

• Actions taken by individuals that resulted in survival, such as escaping or taking refuge

• Decisions made by survivors and their reasons for making those decisions

• Critical fire events, including:

  • Flashover

  • Structural failure

  • Window breakage

  • Alarm sounding

  • First observation of smoke

  • First observation of flame

  • Fire department arrival

  • Contact with other people in the building

An occupant’s ability to recognize danger during a fire is critical to survival.

The occupant must respond appropriately to both perceived and actual dangers. Sensory perception may be affected by:

• Physical condition

• Mental condition

• Consumption of alcohol

• Drug use

Factors Used to Recognize a Fire

An occupant’s actions are based on four factors:

• Sight: Direct view of flames, smoke, visual alarms, or flicker

• Sound: Crackling flames, window failure, audible alarms, a barking dog, crying children, voices, or shouts

• Feel: Rising temperature or structural failure

• Smell: Smoke odor

Possible Responses to a Fire

After recognizing a threat such as a fire or explosion, an occupant must decide how to respond.

Possible reactions include:

• Ignoring the problem

• Investigating

• Fighting the fire

• Signaling an alarm

• Rescuing or assisting others

• Fleeing the fire

• Remaining in place

• Reentering the structure after escaping successfully

The occupant’s final decision is influenced by their state of mind.

Factors Affecting Escape

The ability to escape is affected by:

• How readily escape routes can be identified

• Distance to escape routes

• Fire conditions, including smoke, heat, and flames

• Dead-end corridors

• Obstacles or people blocking the escape route

• Physical disabilities or impairments

Figure 15-17 – Survivor Interviews

Figure 15-17 shows that interviews can lead investigators to important information.

Interviews with survivors may help determine how people behaved before and during the fire or explosion. These interviews can establish:

• Prefire conditions

• Fire and smoke development

• Fuel packages and their locations and orientations

• Victims’ activities before, during, and after discovery of the fire or explosion

• Actions that resulted in survival, such as escaping or taking refuge

• Decisions made by survivors and the reasons for those decisions

• Critical fire events, including:

  • Flashover

  • Structural failure

  • Window breakage

  • Alarm activation

  • First observation of smoke

  • First observation of flame

  • Fire department arrival

  • Contact with other people in the building

Chapter Key Terms

Benchmark events

Events that are particularly valuable as a foundation for the timeline or may have significant relation to the cause, spread, detection, or extinguishment of a fire.

CFD models

Analytical models for fire behavior based on computational fluid dynamics.

Estimated time

An approximation based on information or calculations that may or may not be relative to other events or activities.

Failure mode and effects analysis (FMEA)

A technique used to identify basic sources of failure within a system and to follow the consequences of these failures in a systematic fashion.

Fault trees

Logic diagrams that can be used to analyze a fire or explosion; also known as decision trees.

Hard times

Specific points in time that are directly or indirectly linked to a reliable clock or timing device with known accuracy.

Heat transfer models

Models that allow the investigator to determine how heat was transferred from a source to a target by one or more of the common heat transfer modes: conduction, convection, or radiation.

High-temperature accelerants (HTAs)

Mixtures of fuels with Class 3 or Class 4 oxidizers and thermite mixtures.

Incendiary devices

A wide range of mechanisms used to initiate an incendiary fire.

Incendiary fire

A fire that is intentionally ignited in an area or under circumstances where and when there should not be a fire. (NFPA 921)

Intent

Normally an element of the proof of a crime; the state of mind that exists at the time a person acts or fails to act.

Mass arson

The setting of three or more fires at the same site or location during a limited period of time.

Modus operandi (MO)

The method of operation used by the offender.

Personation

Unusual behavior by an offender, beyond that necessary to commit the crime.

Relative time

The chronological order of events or activities that can be identified in relation to other events or activities.

Sabotage

Intentional damage or destruction.

Scaled timeline

Timeline in which the spacing between the time events being scaled is depicted in a manner that would show the elapsed time between each event.

Serial arson

Multiple arsons by an offender who sets three or more fires, with a cooling-off period between fires.

Serial arsonist

A serial fire-setter.

Serial fire-setter

An individual or group involved in three or more fire-setting incidents.

Soft time

Estimated or relative point in time.

Spree arson

The setting of three or more fires at separate locations with no emotional cooling-off period between fires.

Staging

Purposeful alteration of the crime scene prior to the arrival of police.

System analysis

An analytical approach that takes into account characteristics, behavior, and performance of a variety of elements.

Timeline

A graphic or narrative representation of events related to the fire incident, arranged in chronological order.

Vandalism

Mischievous or malicious fire-setting that results in damage to property.

Zone models

Computer fire models that divide a compartment into two zones: a hot upper zone and a cooler lower zone. (Douglas et al., 2013)