Question Objective: Identify common types of explosives including accelerants and how they are detected. Arson and fire investigations are a unique set of crime scenes for criminal investigators.  Gaining a comprehensive knowledge of how to determine origins of fires, common explosives, and how they are detected, as well as the best methods for investigating a fire/arson scene are the key areas of focus for this chapter.  Because this is such a highly specific type of investigation it is important to know the resources available to assist on the scene.  The criminal investigator should know what characteristics are typical of arsonists, reasons for arson, how to interview suspects and witnesses to an arson scene, and the importance of photographs.  Although this chapter just touches the tip of the iceberg for arson investigations you should be at least familiar to the point you can easily converse about potential indicators of arson at a scene after studying this material. In discussion, answer the following: How is the source of fire determined, along with explosives and accelerants? How do you distinguish burn patterns? Explain the scientific method specific to arson investigations.