The use of X-Ray Computed Tomography to investigate modification in firearms

Addinall, K. (Speaker), Townsend, A. (Speaker), Blunt, L. (Speaker)

Activity: Talk or presentation typesOral presentation

Description

This paper presents the study of criminally modified firearms using X-ray Computed Tomography (XCT), focussing on antique firearms which are increasingly popular with criminals due to the ease of obtainment.

As a firearms licence is not needed for the purchase of antique firearms, due to the fact they cannot fire modern ammunition, it opens up the market to criminals who may come into possession of an antique firearm and then modify it for use. This can be done by either changing the barrel completely i.e. with a smooth bore pipe or re-machining the barrel so that it can accept modern ammunition.

With criminals becoming more aware of the identification procedures for firearms,modifications are likely to become more complex.. Barrels may be modified after each use so that each time it is fired the striation patterns on the bullet will be slightly different, meaning that forensics would not be able to link a specific firearm if it was to be used in multiple crimes.

All of the above make it harder for forensic examiners to identify specific firearms due to the unique individual characteristics they possess after modification.

The use of XCT a 3D model can be produced which allows the examiner to view the inner of the barrel non-destructively. The information obtained includes any markings that may be on the inner such as tool marks, including the depth and length of the markings in addition to any abrasion on the inner surface.

As the tool marks on the inner of the barrel can be examined it means that when the cartridge casing and bullets are also examined a more precise match/exclusion can be made.

Previous methods of identification included 2D imaging or the use of a cast impression of the inner barrel. Both methods are sufficient however 2D imaging loses depth therefore would not be useful when wanting to know how deep certain tool marks are. Cast impressions can cause possible contamination or minor damage to the inner barrel which is preferably avoided to ensure the preservation of evidence.

The above project work will all aid forensic examiners when faced with the task of identifying whether bullets and cartridge cases were fired from a specific firearm. It will allow forensic examiners to view tool marks made on the inner of the barrel which before were unable to be viewed, in addition to crucial information such as the depth of tool marks, which was lost on previous methods. Making the overall identification more accurate.
Period10 Oct 2019
Held at26th Annual Meeting of ENFSI Firearms and GSR working group
Event typeConference
LocationKrakow , Poland
Degree of RecognitionInternational