Fire: What is fire?
 Collecting evidence
 Analyzing evidence
Explosives: What are they?
 Collecting evidence
 Analyzing evidence

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
Fire : rapid oxidation with evolution of heat and light.

Fire
Four components of fire:
 Fuel
 Heat
 Oxygen
 Uninhibited chemical chain reaction

Fire
Four components of fire:
Fuel: can be solid, liquid or gas
 Fuel can only consumed in the vapor state
 Therefore, solids and liquids must first be
“vaporized”
Burning takes place at the surface of solids and liquids.

Fire
Four components of fire:
Heat: Temperature
Oxygen: found in air; can be used up in closed in spaces.
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
Fire Investigation:
First the point of origin is determined:
 Where the fires starts
 Usually contains the most damage.
Once point of origin is determined, the cause of the fire is determined.

Fire > Investigation
Cause of Fire:
 Natural
 Accidental
 Undetermined
 Intentional
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 > Collection
Collection of Evidence
Even in a large fire, accelerant residues of flammable liquids may be left behind.
 Common: gasoline, kerosene, fuel oil
 Rarer: alcohol, paint thinner
Unusual burn pattern may suggest use of liquid accelerant.

Fire > Collection
Collection of Evidence
Accelerant remains can be detected by tracing the point of origin or canine use.
Object containing accelerant must be packaged in air tight container.

Fire > Collection
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
Collection of Evidence
 Along with sample from point of origin, a control sample should be collected.
(material from a different room/location)
 Carpet fibers (synthetics) may be
“petroleum” based.
 Obviously, evidence collection documented with photos, sketches, etc.

Fire > Analysis
Analysis of Accelerants
Gas Chromatography separates components and Mass Spectrometry identifies the components.