I trained as a forensic investigator about two decades ago at the Metropolitan Police Institute in Miami, United States. This is the training college for the Miami Dade Police Department.

During the two-year period of training, I was exposed to many areas of science that I did not know existed in policing. And oddly enough, there are quite a few things we called science that they called ‘junk’. One of those was gunshot residue testing.

The gunshot residue test is the swab taken from a person’s hand to determine if he or she had fired a gun recently. This test is often given to gunmen when they are accused of firing a weapon and are held within a few hours. Most often the test is administered to men wounded or killed in shoot-outs with the police.

The issue, however, is the period before the test is administered. My trainer told me that the reason it is not done is that it allows too many ‘bad guys’ to get away, as the residue, to a large degree, dissipates after 15 minutes. This, therefore, removes the likelihood that their hands will show elevated levels of gunshot residue.

This can, unfortunately, aid the defence of a gunman who is accused of shooting at the police. Or, it can tragically weaken the defence of a police officer who has wounded or killed a gunman in combat.

Low levels of, or no gunshot residue on a gunman’s hand, would suggest that he did not fire. This result occurs likely because in most cases the gunman’s swab is taken many hours after the shoot-out, whether he is alive or dead.

There is also the issue of type of weapon being fired by the offender. Semi-automatic pistols expend powder largely through the ejection port that expels the shell. Other than that, it is largely a sealed tool. However, the hand that holds the gun is not in front of this port. A revolver is not sealed, so the powder will get on the hand.

The problem though, is that Jamaica’s gun of choice is the semi-automatic pistol.

So who does this test aid? And can it be fair if it is administered outside of a 15-minute time period? More importantly, are the shortcomings of this test being explained to judges? And do juries understand its complexity and dependence on a time and type of weapon?

The importance of time of testing in relation to the firing of the weapon that I hear being bounced around the legal system, versus what I was taught is night and day. The standard expressed by the Crime Laboratory Division of Missouri State is testing within six hours. The stated reason is that after this period following the discharge of a gun, analysts would not expect to find gunshot residue on an active person.

Remember though it is elevated levels that are expected if you are alleging that the hand was holding a firing gun, not just presence. So if it is totally gone six hours after firing, then what levels will you find at four hours or five? Certainly not elevated!

The other popular science issue that disturbs me is our odd and puzzling rate of matching the projectiles allegedly fired from Glock handguns to the barrels of Glock pistols. Glock barrels are made by a technique called ‘hammer forging’. Almost all other barrels are made with the use of conventional tools. This process that manufactures Glock barrels does not create the striation marks that the conventional process creates.

Here is the issue: It is striation marks that are used to match a recovered bullet to a gun barrel.

I am not the only one who is concerned about the Glock issue. Los Angeles Police Department’s Chief William Bratton and Commissioner Alan Skobin have also expressed their concern with the difficulty of doing these matches. But, let us hear what a true expert says.

Paul Murphy, an established authority in ballistic science, in his presentation at the International Forensic Technology Symposium in 2009, stated that 80 per cent of examiners get matches less than 10 per cent of the time.

The New York Police Department changed their barrels from Glocks with polygonal rifling because of this issue in 1995. The Miami Dade Police Department developed an entire unique system of identification called Glock Enhanced Bullet Identification because of the crisis.

The sad issue here is that this flawed science is likely to affect almost only licensed Glock owners, and far more often Jamaican police officers.

An officer can be placed at a shooting scene that he denies ever being at. Or, more likely, be implicated when tests show that he fired, even when he denies doing so. This can result in his being charged, or even wrongly convicted.

I believe our ballistic experts are world standard. However, they are limited to the efficiencies of their equipment.

Oddly enough, had this issue been likely to impact gang members and other criminals in any negative way, society would be all over it. However, because the likely victims are lawmen, everyone is silent on this issue, which is in fact no secret.

The Glock is a good gun, and the spent shells are an easy tool of identification. Why then are we having these miracle comparisons made from warheads?

These two areas of junk science stand out and can negatively impact lawmen and other people seeking justice. However, consideration also needs to be given to other areas of forensic evidence, like fibres, likelihood of finding fingerprints on guns, and teeth bite reconstruction – which is being challenged in courts worldwide.

Are we in Jamaica really testing the logic of scientific analysis? Or is it that like many before us we are so mesmerised by men in white lab coats that we disconnect from logic?

Feedback: jasonamckay@gmail.com