What type of evidence will most directly point toward an incendiary fire?

The presence of accelerants, such as gasoline, is the most direct evidence indicating that a fire was intentionally set, or incendiary. Accelerants are substances that accelerate the combustion process and can dramatically influence the behavior of a fire. Their detection at a fire scene suggests that the fire was not solely the result of natural causes or accidental ignition. In forensic fire investigations, the discovery of accelerants is crucial because they provide strong indicators of foul play and support the hypothesis of arson.

While burned wood indicates that a fire has occurred and patterns of soot can provide information about the fire’s behavior and movement, neither directly indicates intentional actions leading to the fire. Similarly, witness accounts of explosions could suggest an unusual event related to the fire but do not specifically confirm the use of accelerants or intent to cause a fire. Thus, finding accelerants is pivotal to establishing that a fire was incendiary in nature.