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Evaluation of GLOCK 9 mm Firing Pin Aperture Shear Mark Individuality Based On 1,632 Different Pistols by Traditional Pattern Matching and IBIS Pattern Recognition
Author(s) -
Hamby James E.,
Norris Stephen,
Petraco Nicholas D.K.
Publication year - 2016
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/1556-4029.12940
Subject(s) - cartridge , matching (statistics) , ibis , poison control , ballistics , statistics , engineering , crash , forensic engineering , simulation , mathematics , computer science , projectile , materials science , mechanical engineering , geology , medicine , paleontology , environmental health , metallurgy , programming language
Over a period of 21 years, a number of fired GLOCK cartridge cases have been evaluated. A total of 1632 GLOCK firearms were used to generate a sample of the same size. Our research hypothesis was that no cartridge cases fired from different 9‐mm semiautomatic GLOCK pistols would be mistaken as coming from the same gun. Using optical comparison microscopy, two separate experiments were carried out to test this hypothesis. A subsample of 617 test‐fired cases were subjected to algorithmic comparison by the Integrated Ballistics Identification System ( IBIS ). The second experiment subjected the full set of 1632 cases to manual comparisons using traditional pattern matching. None of the cartridge cases were “matched” by either of these two experiments. Using these empirical findings, an established Bayesian probability model was used to estimate the chance that a 9‐mm cartridge case, fired from a GLOCK , could be mistaken as coming from the same firearm when in fact it did not (i.e., the random match probability).