Characterization and differentiation of aluminum powders used in improvised explosive devices. Part 2: Micromorphometric method refinement and preliminary statistical analysis

Journal Article · 18 November 2021 · Journal of Forensic Sciences

DOI: https://doi.org/10.1111/1556-4029.14946 · OSTI ID:1832034

Ommen, Danica M.  ^[1]; Baldaino, JenaMarie ^[2]; Saunders, Christopher P. ^[3]; Hietpas, Jack ^[4]; Buscaglia, JoAnn  ^[5]

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1. Department of Statistics Iowa State University Ames Iowa USA
2. FBI Laboratory, Explosives Unit Quantico Virginia USA
3. Department of Mathematics and Statistics South Dakota State University Brookings South Dakota USA
4. Microtrace LLC Elgin Illinois USA
5. FBI Laboratory, Research and Support Unit Quantico Virginia USA

Abstract Aluminum (Al) powder is commonly encountered in improvised explosive devices (IEDs) as a metallic fuel due to its availability and low cost. Although available commercially in powder form, amateur bomb‐makers also produce their own Al powder via simple methods found online. In order to provide investigative leads and forensic intelligence, it is important to evaluate not only the composition of homemade devices, but also to distinguish between the various forms of Al powder they contain. To achieve this goal, a method using automated microscopy in combination with statistical techniques has been demonstrated to have the potential to provide source discrimination and investigative leads in source attribution of Al powders in IEDs. The present research refined this method and investigated 59 industrially and amateurly produced Al powder sources with seven subsamples per source using two traditional linear discriminant analyses (LDA), one with a standard data split for training and testing, and another using leave‐one‐out cross‐validation. Averaging the classification accuracies for the two LDA‐based analyses, LDA has the ability to correctly classify 59.26%, 83.35%, and 80.69% of the samples based on their powder source, type, and production method, respectively. This classification accuracy represents a 3407%, 317%, and 61.38% increase in accuracy from random class assignment, respectively. Further, in most instances of incorrect data attribution to a particular source, the subsample has been misidentified with another sample of the same powder type or production method.

• Sponsoring Organization: USDOE
• OSTI ID: 1832034
• Journal Information: Journal of Forensic Sciences, Journal Name: Journal of Forensic Sciences Journal Issue: 2 Vol. 67; ISSN 0022-1198
• Publisher: Wiley-BlackwellCopyright Statement
• Country of Publication: United States
• Language: English