Crime Scene Investigation

Know the procedure for crime scene investigation well, especially the timeline/Order in which professionals examine the scene (do we ask witnesses first? Do we close off the area?)-Know the advantages and disadvantages of each search method-Know the advantages and disadvantages of each crime scene investigation team

Background requirements for a crime scene analyst

Requires science degree from college/university
Can work in law enforcement or as lab analysts
Certified by International Associate for Identification

Responsibilities of a crime scene analyst

Crime scene processing/evidence collection

Locard's exchange principle

Every contact leaves a trace
Intensity, duration, and nature of materials determine extent of transfer

Direct evidence

Firsthand observations (ex. security footage, witness accounts)

Trace evidence

Refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells

Circumstantial evidence

Indirect evidence that implies a fact (ex. gun is left behind, implying usage of gun)

Physical evidence

Any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator

Biological evidence

Body hair, fluids, plant parts, natural fibers
Reduces suspects into very small groups/individuals

Chemical evidence

Seized drugs, toxicological samples, materials chemistry, and explosives

Class evidence

Material that connects individual/thing to certain group

Individual evidence

Material that narrows down identity to one person/thing

Responsibilities of first responders at the scene

Secure scene
Assist victim/prevent changes to victim
Search for and arrest suspect
Detain and separate all witnesses
Protect/secure crime scene with recordkeeping, barriers, tape, vehicules
Document all movements and alterations

Responsibilities of crime scene investigators at the scene

Perform preliminary scene survey
Use walkthrough as base for reconstruction theory
Note transient + conditional evidence that requires immediate processing
Take note of environmental conditions
Note points of entry/exit
Record initial observations
Assess scene for personnel, precautions/equipment needed
Notify superior officers as needed

Traditional crime scene investigation model

Use of patrol officers/detectives as crime scene technicians

Disadvantages of use of traditional crime scene investigation model

Minimal experience
Time commitment conflicts with regular duties

Advantages of use of traditional crime scene investigation model

Useful if resources are low/demand is low

Crime scene technicians crime scene investigation model

Specially trained, full-time civilian personnel used in investigation

Advantages of crime scene technicians crime scene investigation model

Continuity, specialization, scientific/technical training

Disadvantages of crime scene technicians crime scene investigation model

Minimal investigative experience, lack of global view of investigation

Major crime squad crime scene investigation model

Full-time sworn officers

Advantages of major crime squad crime scene investigation model

Primary assignment, increased experience

Disadvantages of major crime squad crime scene investigation model

Depletion of investigative resources, only major cases handled

Lab crime scientists crime scene investigation model

Laboratory scientists

Advantages of lab crime scientists crime scene investigation model

Superior technical/scientific skills, knowledge of current methods

Disadvantages of lab crime scientists crime scene investigation model

Depletion of laboratory resources, no investigative experience

Collaborative team crime scene investigation model

Use of police officers, technicians, laboratory personnel, medical examiners, and prosecuting officials

Advantages of collaborative team crime scene investigation model

Advanced scientific, technical, and investigative knowledge, shared responsibilities

Disadvantages of collaborative team crime scene investigation model

Extensive resources and comprehensive procedures needed with continual communication

Primary crime scene

The original location of a crime or accident

Secondary crime scene

An alternate location where additional evidence may be found

Medical examiners

Medical doctors that are usually appointed to perform autopsies in highly populated areas

Coroners

Elected officials that may have, but do not have to have, an MD in more rural areas

Detectives

Interview witnesses and consult with the CSI unit, investigate the crime by following leads provided by witnesses and physical evidence

Specialists

Scientists with special training in a specific field (ex. entomologists)

Witness

Someone who sees an event and reports what happened

Questions that must be asked to witnesses

Appearance/identity of perpetrator if possible
Where perpetrator was
Who the victim is
Where crime occurred
Who called the crime
Where they were when crime occurred

Reason for the separation of witnesses

Done to keep objectivity of accounts of witnesses, ensure that they do not talk among each other

Initial survey of crime scene

Includes initial interrogation of witnesses, establishment of location of primary/secondary crime scenes

Crime scene documentation

Permanent recording of the crime scene conditions and physical evidence present

Crime scene documentation includes...

Note-taking
Videography
Photography
Sketching

Things to include while note-taking

Notification information
Arrival information
Scene description
Victim description
Crime scene team

Notification information

Includes date/time, method of notification, information received

Arrival information

Means of transport, date/time, personnel

Scene description

Weather, location type/condition, major structures present, transient/conditional evidence, evidence of recent activity, clothing, furniture, weapons

Victim description

Position, wounds, clothing, jewelry, means of identification on body

Crime scene team information

Note assignments to team members, walkthrough times

Transient evidence

Temporary; easily changed or lost; usually observed by the first officer at the scene

Videography at the crime scene

Document recording with use of placard with case number, date/time, location, and name
Begin with surroundings and include roads to scene
Record smoothly
Use wide-angle views
Record from victim's viewpoint as well

Crime scene photography

Technically proper photography of a crime scene for purposes of complete documentation

Overall photographs

Includes exteriors, aerial photographs, buildings, roads, etc
Includes interiors, doors, and cardinal points

Mid-range photographs

Show spatial relationship and locations of items of evidence

Close-up photographs

Focus on an injury, a weapon, or a piece of evidence to show detail

Three views in forensic mapping

Overhead or bird's-eye view
Elevation view
Cross-projection view

Crime scene sketching

Sketching layout of crime scene and relevant pieces of evidence

Things to include in sketch

Title
Legend
Compass
Scale
Documentation block (case number, offense type, victim name, location, scene description, date/time, name)

Three sketches to be done in crime scene sketching

Elevation/side view sketch
Birds-eye view
Cross-projection sketch (combo of the two)

Triangulation method

Drawing a line from X to Y
Measuring location of evidence based on distance from X and Y

Baseline method

Drawing a line from X to Y
Measuring location of evidence based on distance from the line XY

Polar coordinates method

Designating one wall as X
Measuring angle of the evidence from the wall X

Crime scene search methods

Link
Line
Grid
Zone
Wheel/ray
Spiral

Link method

Based upon linkage theory
Most common/productive method
One type of evidence leads to another in systematic approach

When to use link method

With small and large spaces, indoor and outdoor cases

Line/strip method

Volunteers and search coordinator each search in a separate strip of the crime scene

When to use line/strip method

In large/outdoor scenes

Grid method

Repeating the line/strip method but perpendicular to the first lines
Is effective, but time-consuming

Zone method

Teams assigned small zones that are small/specific to search in

Advantages of zone method

Good for zones with pre-defined areas, search warrants, buildings, often combined with other methods

Wheel/ray method

Investigators move in lines radiating from central point
Limited applications, but good for small, circular crime scenes

Spiral method

Inward/outward searches in a spiral

When to use spiral method

In area without physical barriers, limited applications

Collection/preservation of liquid/arson evidence

Placed in airtight, unbreakable containers

Collection/preservation of biological evidence

Placed in breathable containers to dry out

Collection/preservation of wet/moist evidence

Placed in airtight containers

Paper bindle

A folded paper used to hold trace evidence

Evidence log

A document attached to an item of physical evidence recording the chain of possession (chain of custody) of that piece of evidence

Things to include on evidence log

Case number
Item inventory number
Description of evidence
Name of suspect
Name of victim
Date/time recovered
Signature of collector of evidence
Signature of present witnesses

Chain of custody

A list of all people who came into possession of an item of evidence

Crime scene reconstruction

The method used to support a likely sequence of events at a crime scene by the observation and evaluation of physical evidence and statements made by individuals involved with the incident

Common staged crime scenes

Arson to hide evidence of other crimes
Suicide to cover up murder
Burglary to cover up premediated murder/insurance fraud

Linkage theory

The scene, suspect and victim are all connected by evidence

Corpus delicti

Facts proving that a crime has been committed; body of the victim in a murder case

Modus operandi

A usual way of doing something, especially of a criminal

Macroscopic crime scene

Refers to the entire environment of a crime scene, not limited to the precise location of the crime

Microscopic crime scene

Refers to the immediate, localized area of the place where a crime took place

Once a crime scene is created, it immediately begins to...

Change and decay

Four other classifications of crime scene other than size and location of original criminal activity

Type of crime committed, condition of crime scene, physical location, criminal behaviour associated with scene

Objectives of any crime scene investigation are to...

Observe, preserve, collect, and interpret evidence

The purposes of a crime scene investigation may include...

Linkage of persons, objects, and scenes
Acquisition of investigative leads (physical evidence)
Information on corpus deliciti
Information on modus operandi
Proving credibility of witness statements
Identification of suspects
Identification of unknown substances

Four components of crime scene management

Information, manpower, technology, logistics

Two basic sketch types

Rough sketch and final/finishes sektch

All three techniques of sketching identify...

Two starting, fixed points (ex. trees, utility poles)

The goal of a crime scene search pattern is to...

Provide a systematic structure for ensuring no objects or evidence is missed or lost

Seven S's of crime scene investigation

Securing the scene
Separate the witnesses
Scanning the witnesses
Seeing the scene
Sketching the scene
Searching for evidence
Securing/collecting evidence

Each model of crime scene investigation has advantages and disadvantages based on...

Allocation of personnel and resources
Training and expertise
Crime rates
Types of crimes
Jurisdictional issue
Support services available

The only people (or person) to view the crime scene in its original or most pristine form

First responders

Preliminary scene survey

A walk through the evidence conducted by the crime scene investigator to identify and observe any evidence and the physical bearings of the scene

Forensic photography was popularized due to...

The killings in London attributed to Jack the Ripper (1888)

Crime scene mapping software often includes...

Electronic distance
Determination (also called electronic data collection, or EDC)
Height and slope measurements
Mapping capability
Ability to locate points in three dimensions (including elevation information)

Druggist's fold

Known as the evidence fold, special fold used to hold small and easily lost trace evidence

Data collection

All of the information/documentation obtained at crime scene, from victim/witnesses, physical evidence, patterns/impressions/ condition of the victim