Ballistics is the study of projectile flight paths. When forensic ballistics or ballistic fingerprinting (also known as forensic firearm examination) is utilized in criminal investigations, it aids in the reconstruction of a crime scene involving a firearm. It also allows for the tracking of the weapon used, which can lead to the identification of the culprit(s). Bullets, gunpowder residues, shell casings, guns, and other evidence obtained from the crime scene are heavily used in forensic ballistics.
Forensic ballistic experts are skilled at analyzing such data to derive firm conclusions about the weapon used, the distance, velocity, and angle of fire, and, eventually, the shooter himself. The matching of recovered bullets and their casings to the firearms from which they were discharged has become synonymous with forensic ballistics in crime scene investigations. While present-day criminal drama series may make the use of such procedures appear to be extremely modern, the fact remains that such ballistic work has a long history.
Gunsmiths handcrafted barrels and bullet molds before mass production of weapons began. As a result, each firearm’s exclusivity was unavoidable. This meant that the bullets fired always left distinctive marks that were exclusive to a particular firearm. Thus began the first cases of a bullet being carefully examined to track it back to the gun that fired it. And so was born forensic fingerprinting, the forensic examination of firearms and other evidence (bullets, cartridges, etc.) recovered from a crime scene to link them to suspects or specific weapons used in the crime. The original roots of forensic firearms identification, like any emerging discipline, are shrouded in obscurity.
It’s unlikely that anyone will ever know when it was first noticed that shot bullets from a specific weapon had a set number of evenly spaced impressed grooves, all angled in the same direction and at the same angle and that they were the same on every other bullet fired through that weapon.
Similarly, when the next logical step was to compare the breadth, quantity, and degree of inclination of the grooves with those from weapons of a different type, it will never be known.
The next step, however, required a quantum leap in lateral thinking to demonstrate that all bullets fired from the same weapon bore microscopic stria (parallel impressed lines) that were unique to the weapon.
Cases of bullet identification from the beginning
Bullets fired through different manufacturers and types of weapons, of the same caliber, were impressed with rifling markings of varying patterns, according to an article published in the Buffalo Medical Journal in June 1900 by Dr. A.L. Hall. Dr. Hall, unfortunately, never built on his original article.
Following disturbances in Brownsville, Texas, in which soldiers of the US infantry opened fire, staff at the Frankfort Arsenal were tasked with identifying which weapons were fired. Handbook of Firearms and Ballistics Magnified pictures of the firing pin impressions on the cartridge cases were utilized as a means of identification.
They were able to positively identify 11 of the 39 cartridge casings studied using this method; 8 were from a second weapon, 11 from a third, and 3 from a fourth. The six cartridge cases that remained were not identified. The examiners decided that the recovered bullets lacked any distinguishing characteristics identifying the weapon from which they were fired. The only conclusion obtained was that they were fired from either a Krag or a Springfield rifle, based on the rifling characteristics.
As mass production of weapons and ammunition increased, the rifling process became more standardized. As a result, while a forensic expert could match the rifling markings on a bullet recovered from a crime scene to those on the rifle’s barrel, matching a bullet to a specific firearm made by a certain manufacturer through simple observation became increasingly difficult. As they say, “necessity is the mother of invention!” As a result, the magnified observation of bullets became possible.
In 1902, Oliver Wendell Holmes, who subsequently became a justice of the United States Supreme Court, is reported to have examined a test bullet fired into cotton wool with a magnifying glass to compare its striations with those found on the bullet retrieved from the victim during an autopsy.
Photomicrographs are used. For several years, the staff at Frankfort Arsenal’s pioneering work went unnoticed, and it wasn’t until 1912 that Victor Balthazard achieved the next big advance in this field. In an attempt to identify the weapon from which the bullet was fired, Balthazard took photomicrographs of bullet lands and grooves.
He concluded from these investigations that the cutter used in rifling a barrel never leaves the same markings on successive trips through the barrel. These patterns, which must be unique to that barrel, are then imprinted on any bullet traveling through it as a series of striations. As a result, he reasoned, it is possible to prove beyond a reasonable doubt that a fired bullet came from the barrel of a certain weapon and nothing else. The importance of Balthazard’s work cannot be overestimated, because the entire modern science of bullet detection is based on this concept.
Balthazard’s work, however, featured markings imprinted on fired cartridge cases in self-loading pistols, in addition to matching striations on bullets. The firing pin, breech face, cartridge extractor, and ejector caused the markings he described as exhibiting recognizable stria and markings unique to a specific firearm. He reasoned that a cutting or finishing tool’s final run through a cartridge extractor, for example, left a series of striations that were unique to that extractor. Similarly, finishing strokes with a hand-held file, such as rounding off the firing pinpoint, left marks that were unique to that piece of work.
De Rechter and Mage published a study in the Annales de Medicine Legale in 1923 that highlighted the merits of using firing pin impressions to identify the weapon used. While there was some reference of Balthazard’s work in this paper, it did not fully acknowledge him for his work with self-loading handguns.
Pierre Medlinger mentioned the reproduction of minute imperfections in the breech face on the soft brass of American primers around the same time.
However, the matter was left at that, with no mention of the possibilities of identifying the weapon with which it was fired.
The weapon’s identification is based on the breech face marks. While it was accepted at the time that a fired bullet and cartridge case could be linked to a specific weapon, there was no information available to tell the make and model of a firearm a fired bullet or cartridge case had been fired in.
Heess, Mezger, and Hasslacher rectified this in 1932 by publishing an enormous quantity of data in volume 89 of the Archiv für Kriminologie titled “Determination of the Type of Pistol Employed, from an Examination of Fired Bullets and Shells.”
The American Journal of Police Science published a translated and reprint of this article in 1932. An ‘atlas’ including images of 232 different self-loading handguns, each with an illustration of the breech face and the markings created on fired cartridge cases, was attached to the article. There were also measurements of rifling twist width, number, direction, and angle. This atlas was commercially produced as a series of cards that were updated regularly. Unfortunately, this has been out of print for decades, with copies in high demand as collector’s items.
The use of a comparison microscope was developed. However, it wasn’t until 1925 that a comparison microscope was first mentioned, which allowed for the simultaneous viewing of magnified pictures of two bullets or cartridge cases for forensic comparison purposes. In a study published in the Chicago Police Journal in 1936, Calvin Goddard credits Philip Gravelle with inventing the comparison microscope in 1925. This, he claims, was an evolution of Albert Osborn’s document examination comparison microscope. The microscope was built with a Zeiss optical bridge, Spencer microscope bodies, Leitz eyepieces, Bausch & Lomb objectives, and Remington Arms Company bullet mounts.
Bullet striations are on the circumference of a curved surface, and only a small fraction of this can be accurately depicted in focus on a single photograph. Closed-circuit television (CCTV) and a monitor attached to a video recording device are now standard on modern equipment. It is possible to record the striation match throughout the whole diameter of a bullet using this method.
The first reported case of forensic firearm examination occurred in 1835. That’s when ballistic fingerprinting was used by Henry Goddard to match a bullet recovered from the victim to the real criminal. On closer inspection, he discovered an imperfection on the bullet’s surface that did not appear to be caused by the barrel or an impact. It appeared to be a defect that occurred during the production process. He reasoned that since the shooter would have produced the bullet himself, recovering the bullet mold would be a simple way to prove the shooter’s identity. When the mold found in the suspect’s home matched the marks on the bullet, he was able to locate the shooter with exact precision. This proved as a piece of crucial evidence in convicting the shooter though he did also confess to the crime eventually.