Arson and Fire Investigation

Summary

Fire: What is fire? Collecting evidence Analyzing evidence

Explosives: What are they? Collecting evidence Analyzing evidence

Fire

Arson - The crime of maliciously, voluntarily, and willfully setting fire to the building, buildings, or other property of another or of burning one's own property for an improper purpose, as to collect insurance.

Arson – The crime of starting an illegal fire.

Fire: rapid oxidation with evolution of heat and light.

Fire

Fuel Heat Oxygen Uninhibited chemical

chain reaction

Four components of fire:

Fire

Fuel: can be solid, liquid or gas Fuel can only consumed in the vapor state Therefore, solids and liquids must first be

“vaporized”

Four components of fire:

Burning takes place at the surface of solids and liquids.

Fire

Heat: Temperature

Oxygen: found in air; can be used up in closed in spaces.

Four components of fire:

Chemical Chain Reaction must: The oxidation reaction (burning) must produce

enough heat to maintain burning The fuel mass must be vaporized and drawn

up into the flame.

Fire

First the point of origin is determined: Where the fires starts Usually contains the most damage.

Fire Investigation:

Once point of origin is determined, the cause of the fire is determined.

Fire

Cause of Fire: Undetermined Intentional

Natural Accidental

Who investigates the fire?

Often, the Fire Department will have an investigative team to determine the cause/origin of a fire. (major events = ATF)

Fire > Investigation

What evidence can be collected?

Paper/Trash – not much evidence Accelerant – rapid start Chemical device (road flares, propellant) Electronic device for delayed ignition

Unburned portions of chemical and electronic devices may be left behind.

Fire > Investigation

Even in a large fire, accelerant residues of flammable liquids may be left behind.

Collection of Evidence

Common: gasoline, kerosene, fuel oil Rarer: alcohol, paint thinner

Unusual burn pattern may suggest use of liquid accelerant.

Fire > Collection

Accelerant remains can be detected by tracing the point of origin or canine use.

Collection of Evidence

Fire > Collection

Object containing accelerant must be packaged in air tight container.

Containers for Evidence

Metal cans: airtight, but old cans might rust

Glass Jars: rubber or glued liners may interfere with results.

Special airtight plastic evidence bags: must be properly sealed

Fire > Collection

Along with sample from point of origin, a control sample should be collected. (material from a different room/location)

Collection of Evidence

Carpet fibers (synthetics) may be “petroleum” based.

Obviously, evidence collection documented with photos, sketches, etc.

Fire > Collection

Gas Chromatography separates components and Mass Spectrometry identifies the components.

Analysis of Accelerants

Fire > Analysis