Arson investigations are very difficult due to destruction of crime scene due to fire or explosion. An arson investigator must determine two things, point of origin and cause of the fire. The point of origin is the cornerstone of an arson investigation as any materials found in the area will help determine whether an accelerant or an igniter was used. Examples of the presence of an accelerant would be a charred gasoline can or other combustible materials far removed from an electrical source. An accelerant intensifies a fire and so there are specific signs which to look for during the investigation.
The U.S. Department of Justice gives the following recommendations for all public safety personnel who are investigating a fire. It states first responders should:
- Observe and mentally note evidence that may be present at the
- scene, such as:
- Fire patterns (including multiple fire locations).
- Burn injuries to victims and fire patterns on clothing.
- Trailers, ignitable liquids, or other unusual fuel distribution(e.g., piles of newspapers, furniture pushed together).
- Incendiary/ignition/explosive devices (e.g., lighters, matches,timing devices).
- Shoe prints and tire impressions.
- Broken windows and doors.
- Distribution of broken glass and debris.
- Indications of forced entry (tools and tool marks).
Where there are unusual or suspicious circumstances an investigator will look at possible motive for the fire. Common motives for arson include financial gain, covering a crime and revenge. Less common motive is the psychopathy of the serial arsonist who simply sets fires because it gives him/her pleasure.