Interpol review of forensic firearm examination 2016-2019 (original) (raw)
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Accuracy of comparison decisions by forensic firearms examiners
Journal of Forensic Sciences, 2022
This black box study assessed the performance of forensic firearms examiners in the United States. It involved three different types of firearms and 173 volunteers who performed a total of 8640 comparisons of both bullets and cartridge cases. The overall false-positive error rate was estimated as 0.656% and 0.933% for bullets and cartridge cases, respectively, while the rate of false negatives was estimated as 2.87% and 1.87% for bullets and cartridge cases, respectively. The majority of errors were made by a limited number of examiners. Because chi-square tests of independence strongly suggest that error probabilities are not the same for each examiner, these are maximum-likelihood estimates based on the beta-binomial probability model and do not depend on an assumption of equal examiner-specific error rates. Corresponding 95% confidence intervals are (0.305%, 1.42%) and (0.548%, 1.57%) for false positives for bullets and cartridge cases, respectively, and (1.89%, 4.26%) and (1.16%, 2.99%) for false negatives for bullets and cartridge cases, respectively. The results of this study are consistent with prior studies, despite its comprehensive design and challenging specimens.
Preventing miscarriages of justice: A review of forensic firearm identification
Science & Justice, 2015
The role of a firearm examiner is wide ranging, involving tasks that require scientific understanding in aspects of 19 chemistry, physics and biology. This article aims to provide a critical review of the key scientific principles and 20 practices specifically involved with forensic firearm identification and to discuss how misidentifications have re-21 sulted in cases of injustice. Implementation of quality assured examination practice, demonstration of individual 22 examiner competence and more objective methods of reporting are being adopted by firearm examiners and lab-23 oratories to address some of the criticisms relating to subjectivity and standardisation inherent within the disci-24 pline. The impact of these changes is outlined and further recommendations are made for both examiners and 25 legal professionals to minimise the potential for future injustices involving firearms evidence. Latest research 26 in the field is cited, continuing to support the theory and use of firearm identification as admissible evidence 27 in court.
Accuracy, Repeatability, and Reproducibility of Firearm Comparisons Part 1: Accuracy
arXiv (Cornell University), 2021
Researchers at the Ames Laboratory-USDOE and the Federal Bureau of Investigation (FBI) conducted a study to assess the performance of forensic examiners in firearm investigations. The study involved three different types of firearms and 173 volunteers who compared both bullets and cartridge cases. The total number of comparisons reported is 20,130, allocated to assess accuracy (8,640), repeatability (5,700), and reproducibility (5,790) of the evaluations made by participating examiners. The overall false positive error rate was estimated as 0.656% and 0.933% for bullets and cartridge cases, respectively, while the rate of false negatives was estimated as 2.87% and 1.87% for bullets and cartridge cases, respectively. Because chi-square tests of independence strongly suggest that error probabilities are not the same for each examiner, these are maximum likelihood estimates based on the beta-binomial probability model and do not depend on an assumption of equal examiner-specific error rates. Corresponding 95% confidence intervals are (0.305%,1.42%) and (0.548%,1.57%) for false positives for bullets and cartridge cases, respectively, and (1.89%,4.26%) and (1.16%,2.99%) for false negatives for bullets and cartridge cases, respectively. These results are based on data representing all controlled conditions considered, including different firearm manufacturers, sequence of manufacture, and firing separation between unknown and known comparison specimens. The results are consistent with those of prior studies, despite its more robust design and challenging specimens.
Forensic Science International: Synergy, 2022
This paper describes design and logistical aspects of a decision analysis study to assess the performance of qualified firearms examiners working in accredited laboratories in the United States in terms of accuracy (error rate), repeatability, and reproducibility of decisions involving comparisons of fired bullets and cartridge cases. The purpose of the study was to validate current practice of the forensic discipline of firearms/toolmarks (F/T) examination. It elicited error rate data by counting the number of false positive and false negative conclusions. Preceded by the experimental design, decisions, and logistics described herein, testing was ultimately administered 173 qualified, practicing F/T examiners in public and private crime laboratories. The first round of testing evaluated accuracy, while two subsequent rounds evaluated repeatability and reproducibility of examiner conclusions. This project expands on previous studies by involving many F/T examiners in challenging comparisons and by executing the study in the recommended double-blind format.
Design and results of an exploratory double blind testing program in firearms examination
Science & Justice, 2015
In 2010, the Netherlands Forensic Institute (NFI) and the University of Amsterdam (UvA) started a series of tests for the NFI's Firearms Section. Ten cartridge case and bullet comparison tests were submitted by various external parties as regular cases and mixed in the flow of real cases. The results of the tests were evaluated with the VU University Amsterdam (VUA). A total of twenty-nine conclusions were drawn in the ten tests. For nineteen conclusions the submitted cartridge cases or bullets were either fired from the questioned firearm or from one and the same firearm, in tests where no firearm was submitted. For ten conclusions the submitted cartridge cases or bullets were either fired from another firearm than the submitted one or from several firearms, in tests where no firearm was submitted. In none of the conclusions misleading evidence was reported, in the sense that all conclusions supported the true hypothesis. This article discusses the design considerations of the program, contains details of the tests, and describes the various ways the test results were and could be analyzed.
The use of firearm evidence in the investigation of murder
2018
The continual support of the individuals mentioned below and SAPS as an organisation made it possible for the successful completion of this study. My heartfelt gratitude goes to my supervisor, Dr Horne for the patience, guidance and support she gave me throughout the journey of writing this dissertation. I would like to thank the support I got from my family and friends, especially my mother for her support and love and instilling the importance of education in me. A special "thank you" to my husband Raboya and our sons-Mulanga, Adivhaho and Uhone-for their unconditional love, support and sacrifice of so many hours of our family time. Their love and support is immeasurable and I am deeply indebted to them. I would also like to thank the SAPS for granting me approval and the opportunity to conduct my research within the SAPS. All participants who willingly assisted me with the interviews. Thank you for sacrificing your valuable time, sharing your expertise and knowledge. I would also like to thank God almighty for giving me the ability and strength to persevere and complete this study.