Automated interpretation of comparison scores for firearm toolmarks on cartridge case primers.

Autor: Baiker-Sørensen M; Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB Den Haag, the Netherlands., Alberink I; Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB Den Haag, the Netherlands., Granell LB; Federal Bureau of Investigation, 2500 Investigation Parkway, Quantico, VA 22134, USA., van der Ham L; Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB Den Haag, the Netherlands., Mattijssen EJAT; Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB Den Haag, the Netherlands. Electronic address: e.mattijssen@nfi.nl., Smith ED; Federal Bureau of Investigation, 2500 Investigation Parkway, Quantico, VA 22134, USA., Soons J; National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA., Vergeer P; Netherlands Forensic Institute, Laan van Ypenburg 6, 2497GB Den Haag, the Netherlands., Zheng XA; National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA.
Jazyk: angličtina
Zdroj: Forensic science international [Forensic Sci Int] 2023 Dec; Vol. 353, pp. 111858. Date of Electronic Publication: 2023 Oct 12.
DOI: 10.1016/j.forsciint.2023.111858
Abstrakt: An automated approach for evaluating the strength of the evidence of firearm toolmark comparison results is presented for a common source scenario. First, comparison scores are derived describing the similarity of marks typically encountered on the primer of fired cartridge cases: aperture shear striations as well as breechface and firing pin impressions. Subsequently, these scores are interpreted using reference distributions of comparison scores obtained for representative known matching (KM) and known non-matching (KNM) ballistic samples in a common source, score-based likelihood ratio (LR) system. We study various alternatives to set up such an LR system and compare them using qualitative and quantitative criteria known from the literature. As an example, results are applied to establish a system suitable for a firearm-ammunition combination often encountered in casework: Glock firearms with Fiocchi nickel primer ammunition. The system outputs an LR and a measure of LR uncertainty. The range of possible LR-values is limited to a minimum and maximum value in areas of the score domain with little reference data. Finally, the feasibility of combining LRs of different mark types into one LR for the entire primer is assessed. For the distribution models considered in this paper, different modeling approaches are optimal for different types of similarity scores. For the chosen firearm-ammunition combination, non-parametric Kernel Density Estimation (KDE) models perform best for similarity scores based on the correlation coefficient, whereas parametric models perform best for the Congruent Matching Cells (CMC) scores, assuming binomial and beta-binomial models for KM and KNM score distributions respectively. Finally, it is demonstrated that individual LRs of different mark types can be combined into one LR, to interpret a set of different marks on the primer as a whole.
Competing Interests: Declaration of Competing Interest None.
(Copyright © 2023 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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