Fire Investigation for the Willfully Ignorant

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Oops this won't help the willfully ignorant because, well they are WILLFULLY ignorant. But for all those others who may be interested there is a wealth of information on fire investigations on the interwebs ;)-

For example wikipedia:

Fire investigation, sometimes referred to as origin and cause investigation, is the analysis of fire-related incidents. After firefighters extinguish a fire, an investigation is launched to determine the origin and cause of the fire or explosion. Investigations of such incidents require a systematic approach and knowledge of basic fire science.

The explanatory filter is a systematic approach.

Then we have How to Become a Fire Investigator:

Part detective, scientist, engineer, and law enforcer, the fire investigator represents the collusion of multiple careers rolled into one. It is the fire investigator who must explore, determine, and document the origin and cause of the fire, establish what human actions were responsible for it, then bring authoritative testimony to the courtroom to win a conviction in cases of arson

There is more to be found- just search on "fire investigation" and start reading.