What are the main things to remember in the preliminary investigation of a suspected arson?

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.