Ballistic Fingerprint Examination
Among the various applications in forensic science, ballistic fingerprint examination has become one of the most controversial in recent times. While there is nothing wrong with the primary tool used in ballistic fingerprint examination, and that’s the forensic comparison microscope, it’s the reliability of the technique itself that’s under attack. Can ballistic fingerprint examination truly be the answer to solving gun-related crimes?
What to Know about Ballistic Fingerprint Examination
Ballistic fingerprinting is one of the various tests used on firearms. It is a forensic procedure that focuses on identifying the gun used in a crime case. This is made possible either by looking for similarities between marks made on a cartridge with those found in a gun’s breech and chamber or similarities between striations, a type of fatigue mark, on the bullet and those on a gun’s barrel.
Several questions regarding the identification and classification of a gun can easily be answered with preliminary observations and without use of a forensic microscope. A 9mm bullet cannot undoubtedly come from a 10mm gun while bullets from a Colt 45 obviously cannot come from a Magnum cartridge.
Rifling also differs among models and brands. Rifling refers to the spirally cut grooves found within a gun’s barrel. They vary in shape and number of grooves made as well as in its direction and twist rate.
The machining process from which guns are made also creates unique varying marks on its interior. Wear without tear can also cause marks to appear, but these marks may interfere with the original ballistic fingerprint of the gun.
Cartridges are cylindrical casings of a gun’s bullets or ammunition. If recovered from a crime site, they are easier to examine for ballistic fingerprints than bullets. Firstly, impressions made on cartridges are less vulnerable to deterioration due to use because of their location. Next, when bullets are shot, the force and impact of their release could deform their physical appearance and again compromise the original ballistic fingerprints found on their surface.
If recovered, cartridge cases are often easier to identify than bullets. First, the parts of a firearm that produce marks on cartridge cases are less subject to long-term wear, and second, bullets are often severely deformed on impact, destroying much of the markings they acquire.
Guns, cartridges, and bullets recovered from the crime site will be examined using ballistic fingerprinting software. This program usually allows authorities to compare recovered evidence with previously acquired ballistic fingerprints from other crime sites. Accuracy of matches produced by the program can be increased when a certified firearms examiner confirms it by making comparisons of the actual evidence and not just the photographs alone.
One reason why ballistic fingerprint examination is still an imperfect way of determining the veracity of evidence is because these fingerprints can be subjected to alteration. Replacement of certain parts of the gun can also cause ballistic fingerprints to change. They are not effective with all types of guns as well. Shotguns, for instance, cannot be examined for ballistic fingerprints because plastic wrapping prevents the bullets from making impressions on the barrel.
The Controversy on Ballistic Fingerprint Examination
New York and Maryland are two states requiring ballistic fingerprinting on purchased guns. The laws they’ve passed down haven’t, however, helped them reduce their crime rates so far. The lack of positive results, or more specifically the absence of results, makes many people question the effectiveness of ballistic fingerprint examination.
In a 2001 study conducted by ballistic experts from California, their experiments led to 38% failure when the computer was asked to match cartridges from the same manufacturing brand. This figure went even lower, with a 62% failure, when the computer tried matching cartridges from different manufacturing brands.
The study then declared that automated computer matching systems did not provide “conclusive results” and as such necessitated manual review of potential candidates. They also stated that it is still “unknown” if new cartridges can be matched with cartridges that had already been subjected to use.
Using a Forensic Comparison Microscope
A forensic comparison microscope is used by a firearms examiner to study and compare two samples of ballistic fingerprints in greater clarity and detail. A forensic comparison microscope is also referred to as a stereomicroscope. With a comparison microscope, you actually get two microscopes in one unit and they are linked to each other through an optical bridge. This allows the user to view both samples simultaneously but separately or with a split-type view.
When shopping for a forensic microscope, one must consider the kinds of objective lenses used and whether or not its design is ergonomic.
If you’d like to know more about this type of microscope, http://www.comparison-microscope.com might be just the website you’re looking for.
