The effect of weathering on the forensic comparison of disposable gloves
Rimkus, Claire Lillian
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Disposable gloves are often used by the perpetrators of a crime to prevent the deposition of fingerprints and epithelial cells at a crime scene. When removed and discarded at the scene, these items of evidence are often analyzed by a Trace Evidence Unit. By evaluating basic physical and chemical characteristics, a comparison to a known glove can be made. However, it is unclear whether temperature and weather conditions at a crime scene can alter the characteristics of the glove, and have a detrimental effect on this evidence comparison. In this study, a variety of disposable gloves made of nitrile rubber, natural rubber latex, and polyvinyl chloride were studied to assess the relationship between environmental conditions and polymer characteristics. Samples were placed in evidence envelopes or immersed in distilled water at three different temperatures, and were analyzed after 0, 3, and 6 weeks. Analysis included thickness measurements, stereomicroscopy, and Fourier-Transform Infrared Spectroscopy (FTIR). Results demonstrate that disposable gloves are susceptible to physical changes when exposed to various conditions. A majority of gloves exhibited an increase in thickness measurements at a variety of temperature and moisture conditions. Several gloves — spanning all types and different brands — displayed subtle changes in surface texture and spectral data. Analysis was complicated by the fact that no glove is 100% polymer, but instead contains a variety of additives, including stabilizers, plasticizers, and dyes. Additional characterization with a quantifiable separatory method, such as Pyrolysis-Gas Chromatography/Mass Spectrometry, is therefore recommended to further elucidate the changes that can occur.