Determining the Fire’s Point of Origin: Beyond the Obvious

THE AVERAGE FIRE INVESTIGATOR WILL INVESTIGATE at a minimum hundreds of fires during his career. Some will be extremely extensive operations involving numerous outside agencies and restraints. Others will be single-engine responses with little or no damage involved. The fact is that the extent of the fire often depends on when the fire is discovered and the actions taken when it is discovered. Unless someone uses an accelerant or sets up a scenario for a rapid spread of flames, all fires start at one small point. Sprinkler systems not only greatly reduce the damage of a fire but also help to preserve the initial area of origin. Generally, we are sometimes unable to locate the exact point of origin, which further limits our ability to give a definite cause of the fire. If we enter into an investigation where the scene is untouched, we often can determine the fire’s origin and cause. The greatest ally we have to make this possible is an engine crew or command that allows the investigation to begin before extensive overhaul is underway. Leaving the scene as it is found is paramount in many investigations. Occasionally, we encounter the extreme condition.

Recently, our department responded to such a call. After arriving on the scene, the first-in engine company found the sprinkler system had put out the fire. The crew decided to take no further action until the investigator was able to evaluate the scene. The fire was out because the sprinkler system extinguished the fire in its incipient stage, as designed. This left the room in the same condition as when the fire first started.

The fire investigator arrived and conducted his investigation according to NFPA 921, Guide for Fire and Explosion Investigations. Using the systematic approach, he finally arrived at the room of origin and began to rule out items. When he had eliminated everything in the room, only one possible cause of the fire was left: an intentional human act.