Chemical analysis of fire debris in atypical fire incidents

In atypical fire cases where ignitable liquid residues were undetected using traditional fire debris detection method, analyzing other chemical traces such as the gaseous and volatile organic contents, and liquid and solid components of the debris itself, can shed light on the fire events. The forensic laboratory has broadened the scope of instrumental techniques to analyze the diverse nature of samples from fire scenes. In this paper, we reviewed the laboratory’s analytical findings of fire debris samples submitted from atypical fire incidents in recent years. We demonstrated how multi-instrumental approaches usually employed in chemical unknowns analysis, combined with understanding of the correlation between the detected compounds’ physical and chemical properties and the fire, help trace possible primary ignition sources. In local cases, potential sources of fuel in the initial event of atypical fires were categorized into flammable gases, self-heating materials, reactive mixtures, and combustible substances. However, interpreting analytical results and classifying fuel sources remain challenging as they may be subjected to the scale and complexity of scene debris, altered states, detectability of fuel traces, and the limited comprehension of the laboratory regarding the fire properties and behavior of the detected compounds and parent materials. • Atypical fire cases – typical ignitable liquid residues not detected in fire debris • Multi-instrumental approaches to analyze diverse chemical traces from fire debris • Chemical/physical properties of detected traces essential to understand fire events • Fuel traces identified: Flammables, combustibles, self-heating, reactive materials