Examination of Firearms Review: 2007 to 2010 - Interpol

1. Introduction
This review paper covers advances in scientific methods applied to Firearms
reported since the 15 th Interpol Forensic Science Symposium in October 2007. A
literature search was conducted covering articles published in the main forensic
journals since mid-2007. Two domains are distinguished: Ballistics and
Chemistry.
2. Firearms – Ballistics
2.1 Firearms Identification
In their report of 2009, the National Academy of Science made 13
recommendations in regard to “Strengthening Forensic Science in the United
States: A Path Forward.” (1) While those recommendations are very general,
some of them relate to the discipline of firearms and tool marks identification. The
Association of Firearms and Tool Marks Examiners (AFTE) has taken a stand on
the issues and recommendations raised by NAS (2). Also the National
Association of Criminal Defence Lawyers (NACDL) was preparing a position in
the previously mentioned NAS report. NACDL raises seven areas of concern to
which AFTE was given the opportunity to comment on their draft positioning
paper (3).
2.1.1 Validation studies and statistical foundations
It has always been a desire to strengthen the scientific foundations of firearms
identification so as to increase its acceptance in court.
Buckelton et al. have considered the experimental design for acquiring relevant
data to address the issue of comparing consecutively manufactured tools and
firearms (4). This is interesting as comparing consecutively manufactured tools
and firearms constitute the closest situation that one could encounter in known
non matches. The authors pinpoint some criticisms to this method: 1/ most
studies of consecutively manufactured tools use pristine substrate and optimal
conditions; 2/ the test is seldom blind. The authors make suggestions for test
designs to get more realistic results.
One such study about consecutively manufactured extractors was published by
Lyons (5). The author collected ten extractors from Caspian Arms. These were
consecutively assembled in a Colt 1911A1 pistol. After that the pistol was fired
with each of the extractors in place. The cartridge cases were collected and intercompared.
It was demonstrated that there were enough individual characteristics
to distinguish between the consecutively manufactured extractors. However, it
was also noted that sub-class characteristics carried over from extractor to
extractor. A test was set up consisting of multiple sets with 2 knowns and 1
5