Arson and fire investigation

In 2002, an estimated 44,500 fires were intentionally set in buildings and about 41,000 fires were intentionally set in vehicles such as cars and boats. Total property loss was about 1.1 billion, and the fires caused at least 350 deaths. In structures, about 8.6% of the fires were intentionally set, whereas for vehicles, the percentage was 12.4%. Intentionally set fires, or arson, usually involve an accelerant of some type, as well as an incendiary device used to ignite it, and these two components create the physical evidence forensic chemists work with. Arson fires are also referred to as incendiary fires, which are ignited by an incendiary device. 

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National Advanced Fire. Arson> and Explosion Investigation Seminar... 

Accelerants Fire investigators analyze evidence to determine how a fire began and spread. If arson is suspected, it is likely that accelerants— chemicals that speed the spread of a fire—were involved. 

One of the main jobs of the investigator in a possible arson case is to locate and sample residual traces of accelerants. Accelerants are flammable substances that are used to quickly ignite and spread a fire. They include compounds called hydrocarbons, which contain hydrogen and carbon. Examples of hydrocarbons include petrol, kerosene and diesel. 

Arson investigations The use of NMR spectroscopy has been reported to complement the results of other methods for analyzing debris from suspected arson cases. The type of accelerant used to start the fire can be identified by the relative sizes and shapes of the peaks in different regions of the NMR spectrum - the strictly aliphatic portion from 0 to 2 ppm, the aliphatic moieties attached to aromatic components from 2 to 3 ppm, and the aromatic region from 6.5 to 7.5 ppm. Thus, paint thinner, lighter fluid, kerosene, diesel fuel, and various brands of gasoline all give their own unique patterns. These patterns... 

Heat transfer to the substrate has interesting effects on fire behavior and arson investigation. As shown in Figure 9.16 (top frame), heat may reach deep into a substrate such as wood even when oxygen cannot. The result is pyrolysis ("fire cutting") or decomposition in a reducing environment. We discussed pyrolysis in Section 5.5.2 in the context of an inlet to a gas chromatograph, and the same principles apply here. The products of p)uolysis are different from those of... 

D. R. Redsicker and J. J. O Conner, Practical Fire arul Arson Investigation, 2nd ed., CRC Press, Boca Raton, FL, 1997. 

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