A fire involving a flammable liquid generally evolves more rapidly and attains far higher temperatures than a fire involving Class A combustibles. Fire normally progresses upward and outward from its origin; however, if a flammable liquid has been used, the fire will usually spread over a wide area and may run through small openings and cracks in the floor where the liquid flowed. A combustible gas detector can locate residual combustible vapors in an area where accelerant use is suspected. Large-blister charring or 'alligatoring' indicates that the fire evolved rapidly and produced high temperatures, signs that a liquid accelerant may have been used, and an irregularly-shaped or serpentine burn pattern often results from a flammable liquid being poured on floor surfaces. 'Spalling,' which occurs when trapped moisture in concrete turns to steam and breaks the surface of the concrete, is the sign of rapid and intense heat. Generally, the steeper the angle of the 'V' burn pattern on vertical surfaces, the more rapidly the fire has evolved, and a wide-based V pattern with a corresponding burn pattern on the floor at or near its base is indicative of a rapidly evolving floor-level fire which may have resulted from a liquid accelerant. By using known burn-indicator characteristics of metal and glass items in the area of most intense burning, fire temperatures can be determined. Witnesses to the fire should be consulted to determine the color of flame and smoke in the fire's early stages. Black smoke as well as the color of the flames can sometimes indicate that flammable liquids were burning. While no one of the above indicators can conclusively establish the use of a liquid accelerant, combinations and patterns of the evidence mentioned can strongly indicate the use of such an accelerant. Thirteen bibliographic entries are provided.