In with a bullet

Published: 01 August 2008  12:00 PM
Source: The Engineer Online

The breakthrough has been achieved by a multidisciplinary team from Brighton, Brunel, Cranfield, Surrey and York universities, with funding from the Engineering and Physical Sciences Research Council (EPSRC). Project partners include the Forensic Science Service, BAE Systems and coatings manufacturer Andura.

The tags, which measure 30 microns in diameter, are applied to gun cartridges by being embedded in cartridge coatings made from polylactic acid, sucrose ester and tetrahydrofuran. They then attach themselves to the hands or gloves of anyone handling the cartridge and are said to be very difficult to wash off.

A portion of the tag remains on the cartridge even after it has been fired, which could make it possible to establish a definitive forensic link between a cartridge fired during a crime and whoever handled it.

The current success rates for DNA profiling using evidence from gun cartridges are only around 10 per cent. To date it has been extremely hard to establish such a link because of the difficulty in retrieving fingerprints or significant amounts of DNA from cartridge surfaces.

‘The tags primarily consist of naturally occurring pollen, a substance that evolution has provided with extraordinary adhesive properties,' said Prof Paul Sermon from Surrey University, who led the research.

He added: ‘It has been given a unique chemical signature by coating it with titanium oxide, zirconia, silica or a mixture of other oxides.

'The precise composition of this coating can be varied subtly from one batch of cartridges to another, enabling a firm connection to be made between a particular fired cartridge and its user.’

The team has also developed a method of trapping forensically useful amounts of DNA on gun cartridges. It involves increasing the abrasive character of the cartridge case with micro-patterned pyramid textures, or adding an abrasive grit, held in place by a thin layer of resin, to the cartridge base.

This rough surface is able to retain dead skin cells from a thumb as it loads a cartridge into a firearm.

The technology has been designed to avoid damage to the DNA captured that is caused by temperatures generated as the gun is fired, when heat is rapidly transferred from the burning propellant into the cartridge case and when copper is extracted from the cartridge case by lactic acid in sweat.

The tag and DNA-capture technologies could potentially be available for use within as little as 12 months. There may also be scope to apply them in other fields, such as knife crime, in future.

Comments

As mentioned in the comments, stolen ammo, a black market in older ammo, reloaded ammo, or the simple wearing of disposable gloves would defeat this technological marvel, plus variations in the tagging chemistry would have to cover a fairly large batch which would be divided among many buyers... However this would still give the gun-fearing weenies grounds to ban by legislation (or bureaucratic fiat) the production of non-compliant ammo (as California is banning all lead bullets...), drastically raising the cost of practicing for the law abiding, and tending to price out of the market the poor, who are more likely to live in high crime areas and need defense.
Doug in Colorado: 13 Aug 2008

So all we have to do is persuade all the cartridge manufacturers in the world to adopt this technology and wait for the existing stocks of ammunition to be used up? Have the people that fund and carry out this work had a common sense bypass?
Stephen McKelvey: 13 Aug 2008

Surgical gloves just like the ones the forensic teams in Miami wear would solve this problem for the baddies, but then again I don't think your average assassin or common crook would use factory ammo anyway. Reloaded ammo usually goes through a process of cleaning using an abrasive in a tumbler and a case resizing die, which would remove the carefully placed tags. If handling a round can remove the tags then this certainly will. The money would be better spent going after the illegal guns or looking for a method to tag the weapon.
Dave Williams: 13 Aug 2008

Sounds great, but then the baddies could always wear rubber gloves when handling the ammo.
John Lander: 07 Aug 2008

With more than 20 years to see a result due to the wait for tagged ammunition to come into unlicenced circulation and the degree of handling involved in illegal holdings, best of luck, but don't hold your breath.
J. A. Gordon-Baker: 06 Aug 2008

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