Latent Fingerprint Development in Fire and Explosive Devices: Effects of Volatile Analysis Conditions

Abstract

Introduction: The increasing production and use of improvised incendiary and explosive devices across criminal and military contexts intensifies the need to develop forensic techniques not only for detecting these devices but also for identifying potential perpetrators (Gallegos et al., 2023). Many of these devices incorporate flammable liquids, with gasoline being one of the most accessible examples (Martín-Alberca et al., 2015). The volatile organic compounds (VOCs) released by such substances can compromise the integrity and recovery of dactyloscopic evidence, presenting a significant challenge for forensic investigation.

Aim: To assess the current technical and methodological understanding to identify opportunities for optimising forensic laboratory protocols for analysing fingerprint evidence on materials commonly used in such improvised devices, even under the effects of volatile substances.

Materials and Methods: Three databases were used for the literature search: PubMed, Scopus and ScienceDirect. The applied keywords included “fingerprints”, “volatile compounds”, “flammable liquids”, “improvised explosive devices”, “incendiary devices”, and “dactyloscopy”. Studies that were not peer-reviewed and those conducted in post-detonation environments were excluded.

Results: An improvised explosive device (IED) generally consists of an initiator, a switch, a main charge, a power source, and a container (Grant & Stewart, 2017), whereas an improvised incendiary device (IID) typically comprises a flammable liquid, an ignition system, and a container (Martín-Alberca et al., 2015). IEDs are commonly constructed using metallic and plastic materials (Canfarini et al., 2022), while IIDs are predominantly made of glass and may include paper when chemical ignition mechanisms are used (Martín-Alberca et al., 2015). Research directly addressing this topic is scarce, but one study demonstrated that VOCs originating from flammable liquids, specifically gasoline, can adversely affect latent fingerprints present on glass, even after multiple heat exposures at different intervals, when developed using black magnetic powder (Avissar et al., 2019).

Discussion: No studies have examined the behaviour of fingerprints under VOC exposure on materials other than glass, nor the interaction between VOCs and development reagents. Given that improvised devices may also contain metal, plastic and paper components, expanding research to these substrates and assessing different development techniques in the presence of VOCs is essential. Such work would provide a more comprehensive understanding of fingerprint preservation and clarify the influence of VOCs on the effectiveness of development methods.

Conclusions: Further research into the interaction between VOCs and fingerprint residues on a broader range of materials is crucial, particularly in contexts involving IEDs and IIDs. Strengthening the technical and methodological basis of forensic protocols will improve the reliability of evidence processing and support the accurate identification of individuals, contributing to more robust and scientifically sound forensic investigations.