This article discusses the detection of inorganic gunshot residue (iGSR) particles through scanning electron microscopy with energy dispersive X-ray spectrometer (SEM/EDS) in the discovery step. We calculated the probability that all characteristic inorganic gunshot residue particles (iGSR) go undetected and their dependence on the image pixel resolution setup. We built and validated a iGSR particle detection model that relates particle size with equipment registers, and we applied it to 1,174 samples analyzed by a forensic science laboratory. Our results indicate that the probability of missing all characteristic iGSR particles is below 5% for pixel sizes below 0.32μm2. These values indicate that pixel sizes as great as the double in area that is commonly used in laboratory casework, 0.16μm2, are effective for an initial scanning of a sample as it yields good rates of detection of characteristic particles, which might exponentially reduce laboratory workload.
Cite
@article{arxiv.2211.02634,
title = {False negative probability in iGSR detection: a Bayesian approach},
author = {Martín A. Onetto and Edgardo Carignano and Rodolfo G. Pregliasco},
journal= {arXiv preprint arXiv:2211.02634},
year = {2023}
}