Machine learning (ML) is increasingly shaping forensic science by enabling more accurate and objective
evidence analysis. This study applies ML algorithms to classify gunshot residue (GSR) particles using
spectral data obtained through scanning electron microscopy with energy-dispersive X-ray spectroscopy
(SEM-EDX). Conventional GSR identification relies on detecting characteristic inorganic particles
containing lead (Pb), barium (Ba), and antimony (Sb), which point to firearm discharge residue. Twelve
spectra were collected from four hand swabs taken during a simulated shooting scenario, alongside
control samples that yielded no residue signal. The particles were analysed for elemental distribution and
subjected to ML-assisted classification. A statistical framework combining probabilistic modelling with
likelihood ratios (LRs) was then used to weigh the evidential strength of competing hypotheses. Results
revealed marked differences in elemental composition across samples, underscoring the importance of
rigorous statistical treatment rather than relying solely on visual or qualitative assessment. Three of the
four swab classes offered strong support for GSR presence, yielding high LRs favouring the prosecution
hypothesis. One sample, however, deviated from the model's underlying assumptions, illustrating how
elemental signatures alone can be misleading if interpreted without appropriate methodological
safeguards. Overall, integrating ML with probabilistic modelling offers a robust framework for forensic
GSR analysis. Nonetheless, the findings highlight that methodological rigor cannot be sacrificed for
computational convenience, and analysts should remain attentive to cases where statistical assumptions
break down.