The field of arson analysis continues to develop with more and more precise methods of determining if a fire was set on purpose. The importance of arson analysis can’t be overemphasized, and it is crucial to use a top quality testing organization to accurately assess and confirm (or deny) the suspicion of arson.
Fire investigators collect, classify and compares evidence from the scene of a suspicious fire using specialized equipment utilized by lab technicians and field investigators together. Most states have one or more criminal laboratories functioning under the state’s justice department, public safety and law enforcement agencies. If the case rises to the level of further investigation, the FBI or ATF may make their labs available to investigators. The first step, however, is to carefully examine the site of the suspicious fire.
- Analysts sift through the remains of a burned structure to find concrete evidence to support the arson theory.
- Makeup of fire remains is verified, especially in insurance cases where heavily insured objects may have been taken or replaced with less valuable items.
- Burned documents will be examined under infrared or ultraviolet light
- Any in-place alarm or fire sprinkler system is examined to see if it was tampered with
- All electrical wiring and appliances are assessed for problems
The highly developed science of arson analysis can show:
- The melting point of different burned objects
- The flashpoint of the fire (the temperature at which liquid is able to produce enough vapor to create an ignitable mix)
- Visual examination is used in all investigations to determine whether a door was locked or unlocked when the fire broke out.
- Furniture that remains unburned can often help the investigator determine which in-home materials contributed to the ignition of the fire.
Arson investigators always search for signs of accelerants, using different tests to discover traces of petroleum distillates, gasoline, kerosene, crude oil or diesel fuel.
Vacuum Distillation lets the investigator recover volatile hydrocarbons from water susceptible debris such as charred documents.
Steam Distillation is the best known and oldest method of trapping volatile compounds to be assessed
Solvent Extraction uses different compounds like carbon disulfide to extract and assess debris
Charcoal Sampling is done by inserting a charcoal-coated wire into a container on the arson site, then placing that wire in in a pyrolysis unit to accurately assess debris and hydrocarbons.
Charcoal Trap (Swept Headspace) is a relatively new and highly sensitive method of recovering volatile residue from scene of suspected arson.
The next step is to identify the accelerant used. The technique of gas chromatography separates mixes of organic compounds and determines their physical and chemical properties. Mass Spectrometry uses computer data to even more selectively identify petroleum products in the samples. Chemical incendiaries are very common, but leave the most obvious residues.