Arson is a destructive crime in today’s world, with the capability of destroying valuable property and causing thousands of dollars in damage. There are three types of fire starters – pyromaniacs, arsonists, and juvenile fire starters. Pyromaniacs get some sort of gratification from starting fires and very methodical about it. Arsonists set fires for specific reasons such as profit, revenge, or attention. Juvenile fire starters are under 21 years of age. They usually start fires in their homes, schools, or vacant buildings. Because they are younger, they are often gullible and can be coerced into setting fires for less than a professional arsonist can be hired for.

In any fire, there will be a point of origin, or the place the fire started or was set. The point of origin can be found by locating the spot with the greatest amount of damage. It makes sense that the point of origin will be the most damaged and the extent of damage will lessen the farther away from the point of origin it is located. Even if a structure is completely burned to the ground, a skilled investigator will still be able to locate the point of origin.

Signs of arson:

  • Irregular burn patterns: these indicate that an accelerant was used in the fire. Gasoline and lacquer thinner are examples of accelerants, which are commonly poured on a surface such as the floor and set on fire so the fire will be bigger and spread faster. The picture below is an example of a situation where an accelerant was used on a tile floor.


  • A quickly burning fire: pine wood burns at a rate of ¾ an inch per hour. A quickly burning fire can indicate that an accelerant was used.
  • A claim of an electrical fire: less than 7% of fires are actually results from an electrical fire. Wires should be closely investigated to either back up or disprove the claim.
  • Inventory or possession shortage: often if a homeowner or business owner is planning to burn their property and claim insurance, they will remove the most valuable items. Inventory may be unusually low or the homeowner may have recently removed valuable items from the home.
  • Total destruction of a car: often if the fire begins in the engine block of a vehicle, it will not spread into the passenger compartment on its own. Other signs of arson in a vehicle include cut fuel lines, missing gas caps, or used matches. The springs from the seats of the car can also clue in investigators that the fire was a product of arson. The heat from a car fire alone will not be hot enough to cave in the roof of a car or cause seat springs to sag or become distended. Both of these situations are clues that an accelerant was used in a vehicle fire and was therefore arson. Distended seat springs can be seen below.


In a case of suspected arson, investigators look for three things to convict a suspect – an intentionally set fire, motive, and opportunity, also called the “arson triangle.” Let’s say Bob’s warehouse burns down one night, but it was old and falling apart anyway and in need of repairs tht Bob can’t afford at the moment. Investigators found clues that an accelerant was used – there’s your intentionally set fire. Bob is trying to collect insurance on his warehouse and whatever was in it – there’s the motive. But Bob was out at a bar the night his warehouse burned to the ground – he has an alibi so he had no opportunity to set the fire. This doesn’t mean investigators won’t dig deeper to try to find out who set the fire (maybe Bob hired someone to torch his warehouse), but for now, Bob is in the clear as far as an arson suspect goes.

Arson investigation can be very involved and can take a while, but it is important that it be processed correctly and accurately. If it is not, an arsonist may get away with setting fires and destroying property.

Source: Barracato, John S. Fire…Is It Arson? U.S.A.: Aetna, 1979. Print.

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