Regardless of the number of fire scene investigations you do annually─as many as 100 or less than 10─a fire investigaton must ensure his investigation process is thorough, systematic, comprehensive, and complete every time, Buddy Cales told students at his “Essentials of Fire Investigation” workshop Tuesday morning.
To ensure a fire investigation covers all the bases, Cales strongly recommended that investigators adhere to latest edition of National Fire Protection Association 921, Guideline on Fire and Explosion Investigations (NFPA 921). Although not yet a standard, it is the measure against which which fire investigation actions will be compared in a legal action. He noted that past arson convictions have sometimes been overturned based on investigations at the time that were later found to be based on outdated fire science.
It is important to preplan fire investigations and discover and cultivate relationships with experts who specialize in specific areas such as fiber and DNA evidence.
Investigation conclusions must be based on the scientific analysis of the scene, Cales continued. Although information obtained from witnesses on the scene may be useful, it may not match what the on-scene evidence reveals regarding the fire’s origin. The investigator must also beware of prejudging the case based on other information. For example, he said, knowing that a store that burned down had not been doing well financially before the fire should not be allowed to prejudice one’s investigation from the start. The conclusions of the fire investigation must be based on valid fire science, Cales said.