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.
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