1. Arson & Investigations
North Cobb High School Forensic Science
Arson & Investigations

2. What is arson?
The crime of intentionally setting fire to a building or other property
Legal definition varies place to place

3. Arsonists 90% men 50% juvenilles Profile: 43% involve structures
White male
Teens, early twenties
43% involve structures
30% mobile property
28% crops/timber, fence
Son of Sam
New York City
Timothy McVeigh
Oklahoma City

4. Robert William Fisher FBI 10 Most Wanted Killing wife and 2 children
Blowing up their home
Scottsdale, AZ
2001

5. Famous Arson 16th Street Baptist Church Mississippi Burning
1963, Birmingham, AL
Mississippi Burning
1964

6. What is fire?
The light and heat manifested by the rapid oxidation of combustible materials
A flame may or may not be present
Oxidation: a chemical reaction in which oxygen combines with another substance

7. What makes fire? Fuel Heat Oxygen Chemical chain reaction
Reaction must perpetuate

8. Accidental Fire vs. Arson
Intent
Presence of accelerant (ignitable liquid)
material used to initiate or promote the spread of a fire
most common: flammable or combustible liquids

9. Flammable & Combustible Liquids
Flash point: temperature where a pool of liquid will generate sufficient vapors to form an ignitable vapor/air mixture
Combustible liquid: liquid capable of forming a flammable vapor/air mixture
Flammable liquid: combustible liquid that has a flash point below 80°F

10. Common Ignitable Liquids
Petroleum Products
Gasoline
Kerosene
Alcohols
Cleaners
Other household products

11. A little organic chemistry
Organic chemistry: carbon + hydrogen + other stuff
Combustion reactions: carbon compounds + O2
Ignitable liquids: long carbon chains
Kerosene: between 9 and 16 carbons in a chain
TNT: trinitrotoluene

12. Explosives High or low: High: function unconfined
Normally require shock wave from a detonator to ignite
Examples: TNT, PETN, RDX
Low: must be confined to explode
More easily ignited
Examples: black gunpowder, pyrotechnic mixtures

13. Bombs May include items within that become shrapnel High Explosive
Low Explosive