Accelerants in the blood of 73 cadavers found in wreckage after fire were analyzed by gas chromatography (GC) and a combination of gas chromatography-mass spectrometry (GC-MS) to decide whether accelerants containing petroleum components had been used and whether the cadavers had been exposed to fire before or after death. In 16 of 26 cases in which accelerants were used to start a fire before death, accelerants were detected in the blood. In 7 cases in which accelerants were used to start a fire, the victims were determined to have been exposed to the vapor of accelerants after death because no accelerants were detected in the blood, no soot was found in the airways, and carboxyhemoglobin (COHb) concentrations were not higher than those found in smokers. In 9 of 34 cases in which accelerants were suspected to have been used to start a fire before death, accelerants were detected in the blood. When soot is not detectable by the unaided eye in the airways of a victim found in debris of a fire in which the use of accelerants is suspected, or the COHb concentration in the blood is no higher than in a smoker, analysis of accelerants in the blood seems to be helpful in determining the cause of death and whether inflammable were used.