Interpretation of chemical data from glass analysis for forensic purposes. (25th June 2020)

• Record Type: Journal Article
• Authors: Akmeemana, Anuradha; Weis, Peter; Corzo, Ruthmara; Ramos, Daniel; Zoon, Peter; Trejos, Tatiana; Ernst, Troy; Pollock, Chip; Bakowska, Ela; Neumann, Cedric; Almirall, Jose
• Other Names: Levine Barry K. guestEditor.
• Is Part Of: Journal of chemometrics. Volume 35:Number 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-06-25
• Subjects: calibrated likelihood ratios -- elemental analysis -- glass evidence interpretation; Chemistry -- Mathematics -- Periodicals; Chemistry -- Statistical methods -- Periodicals; 542.85
• DOI: 10.1002/cem.3267
• Languages: English
• ISSNs: 0886-9383

Abstract

Abstract: The aims of evaluating forensic evidence are to provide a transparent, coherent, and unbiased opinion of the value of the evidence to fact‐finders. Measurements from glass evidence in a hit‐and‐run, for example, can help decide if a particular vehicle was involved in the accident. The evaluation involves the comparison of the physical, optical, and chemical properties of the glass recovered from the broken window with glass fragments suspected of originating from the window. A standard method (ASTM E2927‐16e1) describes a consensus‐based approach to sampling, sample preparation, quantitative analysis and "match" criterion for comparison of chemical properties. The result is a binary decision of either finding a difference in the elemental composition (exclusion) or a failure to exclude, based on elemental composition. This study demonstrates the utility of likelihood ratio (LR) calculations using novel datasets of glass samples of known manufacturing history. The LRs calculated from comparing glass manufactured at three different plants over relatively short periods (over 2‐6 weeks) range from very low values (LR ~ 10 −3 ) when the glass are manufactured at different plants or manufactured weeks‐months apart in the same plant to very high values (LR ~ 10 3 ) when the glass samples are manufactured on the same day. Although the glass samples being compared may not originate from the same broken window source, they do exhibit chemical similarity within these lower and upper bounds and the LRs presented here, for the first time, closely correlate chemical relatedness to manufacturing history, specifically the time interval between production. The work presented here supports the use of the match criteria recommended within ASTM E2927‐16e1 and provides a data‐driven path forward to expand on the interpretation of glass using LRs. Abstract : This study demonstrates the utility of likelihood ratio (LR) calculations to compare glass fragments and better assess the weight of glass evidence. The comparison of three different manufacturing sources of glass and represented by >500 different samples that were manufactured over a 2 to 6 timeframe result in a range of LR values from very low (LR ~ 10 −3 ) when the glass are manufactured at different plants or manufactured weeks‐months apart in the same plant to very high (LR ~ 10 3 ) when the glass samples are manufactured on the same day. The LRs presented here, for the first time, closely correlate chemical relatedness to manufacturing history. In addition, we demonstrate the utility of both the LR approach and the previously reported ASTM E2927‐16e1 match criteria to correctly associate glass fragments that originated from the same source and to correctly discriminate glass fragments that originated from different sources.