Explosive Device Reconstruction through Chemical and Trace Evidence Analysis: A Homicide Case Investigation

Background Post-blast forensic investigations involving improvised explosive devices (IEDs) pose significant analytical challenges due to the degradation, dispersion, and contamination of explosive residues. This study reports on a homicide case in which a homemade explosive (HME) device was used, focusing on the systematic recovery and chemical analysis of trace evidence from highly degraded exhibits collected five months after the incident. Case presentation This study presents a homicide case in which a homemade explosive (HME) device was deployed in an agricultural field, resulting in the death of a single victim. The suspects allegedly used bombs containing fragmentary materials. Evidence, including soil, debris, metallic fragments, jute thread, stone chips, the victim’s clothing, and burned skin, was recovered five months after the incident under degraded conditions. Sequential solvent extractions (ether, acetone, water, sodium hydroxide, and pyridine) were performed, followed by chemical tests, Thin Layer Chromatography (TLC), and Fourier Transform Infrared Spectroscopy (FTIR). Analytical results confirmed the presence of low explosive constituents—potassium nitrate, ammonium nitrate, metallic aluminium, and elemental sulphur—in multiple exhibits. No high explosives or diesel fuel were detected. Physical evidence supported the use of a fragmentation-oriented IED, designed to increase lethality through shrapnel dispersal. Despite significant sample decomposition, maggot infestation, and thermal alteration, the adopted protocols enabled the reliable detection of explosive residues, aiding in the reconstruction of the device and corroborating witness statements. Conclusion This investigation demonstrated the effectiveness of integrated chemical analysis and trace evidence examination in post-blast homicide cases, even with heavily degraded samples and delayed submission. The combination of sequential extraction methods and multi-technique instrumental analysis provided robust and probative findings, confirming the use of nitrate-based HME with added fragmentation materials. This case highlights the importance of meticulous evidence collection, comprehensive analytical approaches, and adaptability of forensic protocols to challenging post-blast scenarios, thereby enhancing investigative and prosecutorial outcomes in explosive-related crimes.