by • August 18, 2016 • No Comments
In the forensic sciences, the discoquite of a single fact can convict a criminal or let an innocent man walk free. This is particularly significant in gun crimes and a team of scientists at Flinders University in Australia have created a new technique for analyzing gunshot residue that is so sensitive that it is actually possible to match residue with a specific brand of ammunition.
As fans of the CSI shows understand, ballistics is a significant field of the forensic sciences. Beginning with such easy tests as via microscopes to show that a particular bullet was fired by a particular gun, scientists have moved on in the past century to such details as the distance the gun was fired at, the oil that lubricated it, and the residues left behind by the fired ammunition.
Firearm residue is a particularly significant friend of the police forensic scientist for the reason these byproducts of ammunition propellants can link a particular man to a particular weapon during a particular time period. Detecting and analyzing these residues once relied on easy chemical tests, but over the years additional effective tests were created via neutron activation, atomic absorption spectrophotometry, inductively coupled plasma weight spectroscopy, atomic force microscopy, and, many that successfully, scanning electron microscopy with energy dispersive analysis by x-ray detector (SEM-EDX).
What all of these tests are looking for are the leftovers of a cartridge firing. Modern firearms use a rigorous mixture of smokeless propellants, primers, flash suppressors, deterrents, and others created up of different types of organic, mineral, and metallic compounds. When the propellant burns at a temperature of over a 1,000° C (1,832° F), these are manyly turned into carbon dioxide, carbon monoxide, and steam, but traces of the propellant metals, organics, and silicas, along with lubricants and metals of the cartridge casing are left behind – frequently in the form of microscopic nodules.
What the Flinders team is working on is the round glass fragments created by the gunshot. Under the way of Flinders University’s Professor Paul Kirkbride, the team is studying how to determine how gunshot residues are deposited on suspects, and how to select glass fragments and match them to particular brands of ammunition.
They do this by via two quite sensitive techniques called Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and the Sensitive High Resolution Ion Microprobe (SHRIMP). As the names suggest, they use ions to scan samples and determine not just the elements present, but the isotopes. By measuring the ratio of these isotopes in the glass fragments, they can be matched against the isotopes in brands of cartridges with the precision of fingerprints. In this case, it is actually .22 ammunition, that is the many commjust utilized in Australian gun crimes.
“We’ve shown matching characteristics in the trace elements and isotopes discovered in glass fragments in the residue left on the shooter, in the injure and in the specific batch or brand of ammunition,” says Professor Kirkbride. “This is like a fingerprint, that can not alter preceding, during or after the gun is fired.
“Eventually we hope to provide law enforcement agencies with the ability to select not just the brand of ammunition, but in addition the location of make and points of distribution, that all offer significantly towards selecting the purchaser.”
The results of the team’s research can be presented upcoming month at an international conference in New Zealand.
Source: Flinders University
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