Since firefighters have initial contact with persons reporting a fire and with the scene itself, it is vital that they obtain witness reports of the early stages of the fire, document witness data, and observe the progression of the fire for signs that may be indicators of fire origin. Furthermore, firefighting activity distorts much of the scene and obliterates clues needed by the fire investigator, and for this reason, cooperation and information exchange between the two are crucial. The work of fire investigators begins after a fire has been extinguished and requires many hours of unpleasant and exacting physical activity in addition to extensive knowledge and reasoning ability. Mutual understanding of each other's responsibilities, challenges and skills should promote an effective working relationship between firefighters and fire investigators. Four footnotes and seven bibliography items are given.