Arson

ARSON - RECORDING / DEVELOPING

Of all of the different crime scenes, arson can be one of the hardest to obtain evidence from because of the possibility of the evidence burning. One of the oldest crimes known, arson is defined by the Uniform Crime Reporting Program, as "any willful or malicious burning or attempt to burn, with or without intent to defraud, a dwelling house, public building, motor vehicle or aircraft, personal property of another, etc" (Crime Index Offenses Reported). Contrary to the belief

of many people, fires dont always destroy evidence entirely; "furthermore, incendiary and suspicious fires don't typically destroy all the evidence. In more than half of all the incendiary and suspicious structure fires that occurred between 1991 and 1995, there was no flame damage outside the room of origin. Incendiary and suspicious fires are more likely than most other fires to spread beyond the room of origin, but the differences in likelihood are small. In 40 percent of incendiary and suspicious structure fires, in fact, there's no flame damage beyond the immediate area of origin. If useful evidence were available, the fires would probably leave some of it untouched" (Hall). It is crucial in an arson case that any responding officer or investigator record and develop as much evidence as possible, to determine whether they have a case or not.

Like in the other crime scenes in which you would search for fingerprints or shoeprints; arson investigators search for residue of flamible liquids or substances or devices used to start fires. The flammable

liquids are known as accelerants and the devices used to start the fires are called igniters. In eighty percent of arson cases gasoline is the most commonly used accelerant and the most commonly used igniters are matches When searching for the residue of accelerants or igniters investigators tend to look on floors because during fires the liquid drops to areas with the lowest temperatures; which in fires is the floor.

When responding to a fire scene, investigators can go about two ways for detecting whether or not this is a case of arson. The two forms that investigators go about is by either their own sense of smell or by using a device called a catalytic combustion detector. "Arson examinations can determine the presence of ignitible liquids introduced to a fire scene. Examinations of debris recovered from scenes can identify gasoline, fuel oils and specialty solvents" (FBI - Laboratory Manuel). Gasoline has a very distinct smell that makes its stand out to the human sense of smell. Eventhough using your sense of smell can result in an immediate determination of the case, there are two major problems to this method of detecting arson. The first problem being that the smell of gasoline might have been masked by a stronger odor, making if difficult to determine the true smell. The second problem is that many times it is just an inconveniance if not even impossible for an investigator to sniff floors or areas destroyed by the fire. A catalytic combustion detector is a widely used device, that uses a combination of the vapors, some heat and combustible