1. Arson and Fire Investigation

2. Summary Fire: What is fire? Explosives: What are they?
Collecting evidence
Analyzing evidence
Explosives: What are they?
Collecting evidence
Analyzing evidence

3. 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.

4. Fire: rapid oxidation with evolution of heat and light.

5. Four components of fire:
Fuel
Heat
Oxygen
Uninhibited chemical chain reaction

6. 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.

7. 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.

8. 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.

9. Who investigates the fire?
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)

10. What evidence can be collected?
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.

11. Collection of Evidence
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.

12. Collection of Evidence
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.

13. Containers for Evidence
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

14. Collection of Evidence
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.

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