Fire and explosion incidents occur far too frequently every year in the United States. They occur in residences, commercial buildings, manufacturing facilities and chemical plants alike. These incidents cause serious injury, fatality, and large dollar loss as a result of property damage and business interruption. Determining the root cause of the fire and/or explosion is important in the prevention of future recurrences, assessing liability and preparing for potential future claims. This paper addresses the role of the forensic engineer in the effective investigation of fires and explosions involving gas and flammable liquids.