Arson, Fire Investigation, and Explosives: Key Concepts and Evidence Analysis

What three elements are represented in the Fire Triangle?

Heat, fuel, and oxygen

How is fire defined?

As a rapid oxidation process with the evolution of heat and light.

What additional element is included in the Fire Tetrahedron?

Chemical chain reaction

What is arson?

One of the most serious and costly crimes, defined as the intentional setting of fires.

What percentage of arson fires occur outdoors?

50%

What demographic accounts for half of all arson arrests?

Juveniles

What are the four main causes of fire?

Natural, accidental, undetermined, and intentional

Who typically investigates the cause of a fire?

The Fire Department's investigative team

What is the first step in fire investigation?

Determining the point of origin of the fire.

What types of evidence can be collected at a fire scene?

Accelerants, chemical devices, and unburned portions of devices.

What are common accelerants found in fire investigations?

Gasoline, kerosene, fuel oil

What is the purpose of gas chromatography in fire investigations?

To separate components of accelerants for analysis.

List the five stages of fire progression.

Incipient phase, growth phase, fully developed phase, decay phase, extinction phase.

What are the classes of fire based on fuel type?

Class A: solid fuels, Class B: liquid fuels, Class C: gaseous fuels, Class D: metals, Class E: electrical components.

What is the difference between high explosives and low explosives?

High explosives detonate at high velocities; low explosives deflagrate at lower velocities.

What is an initiating explosive?

An explosive that is sensitive to detonation.

What is the Griess test used for?

To detect the presence of nitrates and nitrites in explosive residues.

What characterizes a high order explosion?

It occurs at or near its maximum theoretical detonation velocity.

What factors can lead to a low order explosion?

Old explosives, improper construction, excessive moisture, or improper placement.

What is the significance of the depth of char in fire investigations?

It is used to evaluate fire spread and estimate the duration of a fire.

What is a common example of a low explosive?

Black powder

What is the detonation velocity range for high explosives?

Greater than 1,000 meters per second.

What is the role of accelerant residues in fire investigations?

They can indicate the use of flammable liquids in starting a fire.

What must be done with objects containing accelerants during evidence collection?

They must be packaged in airtight containers.