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. 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

Analytical chemistry is often used to examine samples from a fire scene for the presence of flammable / ignitable liquids that have been deliberately applied to accelerate a fire and that can indicate the cause of a fire as arson.