Investigations of fire-damaged sites may have many objectives, including the collection of evidence where arson may be suspected, or the establishment of a likely cause where issues of public safety may arise. Arson investigations may be particularly challenging, because evidence is likely to be destroyed in the fire or contaminated in firefighting operations.
Investigative work will focus on the ‘fire triangle’ of oxygen, fuel, and source of heat or ignition, and in cases of arson at least one of these will have been tampered with. A fire accelerant such as petrol and gasoline or other liquid fuel may have been used, and traces of these can remain detectable even after a major conflagration. Highly-trained sniffer dogs are a traditional resource used in these cases, but these animals may not be available when needed and have limited reporting powers.
Hand-held VOC detectors from ION Science use the most advanced photoionization detection (PID) technology to identify trace quantities of volatile organic compounds and hydrocarbon residues. These devices can be deployed rapidly and safely, testing areas between floorboards and under carpets where residual traces of accelerant or ignitable liquid residue (ILR) may remain.
Where positive indications of accelerant or ILR are discovered, samples should be taken and carefully stored for subsequent laboratory analysis, often by headspace sampling and gas chromatography.