Many offenders are well aware of common trace evidence used in close personal assault casework and thus attempt to limit transfer of evidence such as DNA and/or fingerprints at a crime scene. However, perpetrators typically overlook the potential transfer of cosmetic components such as shimmer or glitter during a personal assault. This project focuses on developing a characterization scheme to aid in the identification of transferred shimmer and glitter particles collected from a potential suspect, victim, or crime scene. The project will aim to distinguish those components and identify features unique to individual sub-classes.<br/><br/>In this study, glitter and shimmer samples were analyzed using a compound microscope to identify features of area, perimeter, diameter, and thickness. Each feature provided another layer of identification for the glitter and shimmer particles. Samples were also analyzed using scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS). Glitter is typically comprised of tiny pieces of cut polyester films, which may or may not include aluminum, and are painted with pigments approved by the Food and Drug Administration. Therefore, SEM-EDS was used to determine the elemental composition of such pigments.<br/><br/>Similarly, shimmer is comprised of metal-oxide coated mica and SEM-EDS was used to determine the composition of the coatings. Differences were observed between samples comprised of different metals. Additionally, SEM-EDS was used to distinguish among various types of mica used in the manufacturing of shimmer products. Muscovite and synthetic mica are most common in the cosmetics industry, both being comprised of different complex aluminosilicate crystals. Finally, multivariate statistics was performed via hierarchical cluster analysis, principal component analysis, and linear discriminant analysis to determine classification rates of the model. The characterization model will allow for future classification of real world samples.

Identification of glitter and shimmer cosmetic particles using SEM-EDS

2019 Spring National Meeting

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