Citation

Law EF, Morris KB, Jelsema CM. Forensic Sci. Int. 2018; 290: 56-61.

Affiliation

Department of Statistics, West Virginia University, P.O. Box 6330, Morgantown, WV 26506, United States.

Copyright

(Copyright © 2018, Elsevier Publishing)

DOI

10.1016/j.forsciint.2018.06.010

PMID

30015280

Abstract

The Association of Firearm and Toolmark Examiners recommends a minimum of two test fires be performed when an unknown firearm is submitted to a laboratory prior to doing a comparison with a cartridge case collected from a crime scene. Limited research has been performed to determine how many test fires are necessary to be representative of the match distribution of a firearm. Various makes and models of firearms comprising five calibers were tested using a hybrid equivalence test to determine how many cartridge cases were required to represent the match distribution of an unknown firearm based on both breech face and firing pin correlation scores from an IBIS^® Heritage^TM System. The same general trend was observed for each caliber of firearm where the equivalence percentage increased from 10 to 30 cartridge cases. Overall, 15 cartridge cases are sufficient for above an 80% probability of representing the full match distribution for an unknown firearm. To approach full equivalence, 25 cartridge cases are enough because 30 cartridge cases were not found to be significantly higher in equivalence percentage for any caliber of firearm tested.

Copyright © 2018 Elsevier B.V. All rights reserved.

Language: en

Keywords

Breech face; Equivalence test; Firing pin; IBIS(®); Test fires