Design and results of an exploratory double blind testing program in firearms examination

W Kerkhoff; R D Stoel; C E H Berger; E J A T Mattijssen; R Hermsen; N Smits; H J J Hardy

doi:10.1016/j.scijus.2015.06.007

Design and results of an exploratory double blind testing program in firearms examination

Sci Justice. 2015 Dec;55(6):514-9. doi: 10.1016/j.scijus.2015.06.007. Epub 2015 Jul 6.

Authors

W Kerkhoff¹, R D Stoel², C E H Berger³, E J A T Mattijssen², R Hermsen², N Smits⁴, H J J Hardy⁵

Affiliations

¹ Netherlands Forensic Institute, Netherlands Forensic Institute, NFI, The Hague, The Netherlands. Electronic address: w.kerkhoff@nfi.minvenj.nl.
² Netherlands Forensic Institute, Netherlands Forensic Institute, NFI, The Hague, The Netherlands.
³ Netherlands Forensic Institute, Netherlands Forensic Institute, NFI, The Hague, The Netherlands; Leiden University, Leiden, The Netherlands.
⁴ VU University Amsterdam, VUA, Amsterdam, The Netherlands.
⁵ University of Amsterdam, UvA, Amsterdam, The Netherlands.

PMID: 26654088
DOI: 10.1016/j.scijus.2015.06.007

Abstract

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.

Keywords: Blind testing; Bullet and cartridge case comparison; Fake cases; Proficiency test.