Arson & Investigations North Cobb High School Forensic Science Arson & Investigations
What is arson? The crime of intentionally setting fire to a building or other property Legal definition varies place to place
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
Robert William Fisher FBI 10 Most Wanted Killing wife and 2 children Blowing up their home Scottsdale, AZ 2001
Famous Arson 16th Street Baptist Church Mississippi Burning 1963, Birmingham, AL Mississippi Burning 1964
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
What makes fire? Fuel Heat Oxygen Chemical chain reaction Reaction must perpetuate
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
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
Common Ignitable Liquids Petroleum Products Gasoline Kerosene Alcohols Cleaners Other household products
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
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
Bombs May include items within that become shrapnel High Explosive Low Explosive