With technology continually advancing, forensic investigators are now able to gather a host of information from a bullet, bullet fragments, or bullet tracings left at a crime scene. This branch of forensic science is called ballistics, and it examines the bullet's launch, trajectory, and effects. With sophisticated technology, forensic scientists can link specific firearms to their crimes. Below, we discuss how forensic ballistics enables investigators to solve gun crimes.

How Is Ballistics Used in Forensic Science?

The field of forensic science called ballistics deals with the examination of firearms used to commit crimes. It typically involves looking at the unique markings left on the bullet that can be used in forensics investigations. However, ballistics can also be the study of a bullet’s trajectory and damage.

When bullets or fragments are found at a crime scene, they are collected as evidence and sent to forensic ballistics experts. These analysts will examine the bullet’s rifling to identify the firearm (or which type of firearm) was used in the commission of the crime.

“Rifling” refers to the lands and grooves created inside the barrel of the gun during manufacture. When the bullet passes through the barrel, these unique markings will be transferred to the bullet. Forensic science ballistics experts can use these identifiable patterns to connect a gun to the crime in question.

Types of Ballistics Currently Used

There are currently three categories of ballistics: internal, external, and terminal. Internal ballistics examines the bullet’s path from when the trigger is pulled to the point when the bullet reaches the end of the gun barrel. External ballistics depicts the flight of the bullet through the air. Finally, terminal ballistics evaluates the bullet’s behavior once it meets its target.

Characteristics of Bullets Used in Forensic Science Ballistics

Forensic ballistics experts will compare two bullets based on two categories: class characteristics and individual characteristics. Class characteristics are the features of a bullet that can be used to identify any number of bullets, regardless of the specific firearm they were ejected from. These characteristics include the caliber, direction of the rifling, and the number of lands and grooves.

While class characteristics of a bullet alone cannot reasonably link a particular gun to a crime, the individual characteristics are more telling. These characteristics are the features of the bullet that can be connected to a specific source with a high degree of certainty. These marks or imperfections are often due to the corrosion, damage, or tools used to create the land and grooves in the firearm.

Firearm examiners will often note the unique markings on the evidence bullet and then fire test bullets from the suspect’s gun in their lab to determine if the same features appear on the test bullets. If the evidence bullet and test bullet each have similar class and individual characteristics, the conclusion that the evidence bullet was fired from the suspect’s gun can be drawn.

Specific Ways Ballistics Is Used to Solve Gun Crimes

Firearm analysts can use bullet fragments, gunshot residue, fingerprints, the bullet’s trajectory, and the subsequent damage to recreate the events of a crime.

Examination of Bullet Fragments

Forensic ballistics specialists are tasked with examining bullet fragments and casings to identify the firearm that the bullet was discharged from. Using a forensic microscope, they examine the evidence, looking for engravings (unique scratches and marks) left on the bullet during the rifling stage when discharged from the gun. These distinct engravings can allow the firearm examiner to tie the bullet to the gun.

If a cartridge case has been recovered from the scene of the crime, the forensic specialist can look for unique markings that can be used in the forensics investigation. These indentations can be left on the casing’s soft surface by the firing pin, the extracting pin, or the ejector. If the specialist can capture images of these impressions or tool marks, they can link a particular firearm to a crime scene.

In the lab, a forensic comparison microscope is used to compare two separate bullet fragments or casings to each other. This specialized microscope makes forensic ballistics possible because it offers a split view of two different objects at once. In the event that the specialists have the firearm in question in their possession, they can fire a bullet in their lab and then compare the two bullets using this comparison microscope.

Detection of Gunpowder Patterns

Forensic ballistics experts can use the distinct patterns gunpowder residue leaves behind on objects close to the barrel to link criminals or guns to the crime. These patterns can be compared to other criminal cases being investigated or experiments performed in their labs.

Discovery of Fingerprints

In addition to examining bullet fragments for distinct impressions, ballistics experts can recover fingerprints from the surface of the pieces found. It's likely the gunman handled the bullets without gloves, leaving sweat and salt from his fingers behind. Exposing the fragments to superglue fumes and fingerprint powder reveals fingerprints that can then be run through a fingerprint database to discover a suspect.

Analysis of Trajectory

Recreating a crime scene that involved the use of a firearm requires experts to determine the bullet’s trajectory. When they know where the bullet ended up, they can use string or lasers to ascertain its flight path. This information can tell law enforcement agencies details on the shooter’s position, height, etc., possibly the position of the victim, and more.

Examination of Tissue Damage

Even if forensic specialists cannot get information from bullet fragments, they can examine the wounds inflicted on the victims. The tissue damage resulting to the skin or bone can reveal details about the bullet type and how far and fast the bullet traveled. Microscopic investigations are especially beneficial in examining marks left on skeletal bones by the bullet. These analyses can help investigators develop a more complete picture of the events that occurred during the crime.

Solving Gun Crimes with Comparison Microscopes

Advancements in technology have enabled new digital techniques for performing forensic ballistics. Comparison microscopes may not be new technology in any sense of the word, but they have seen remarkable improvements over the years. Comparison forensic microscopes allow labs to run and document vital analyses for gun-related crimes. With this type of microscope, they can look at such things as the tool mark impressions left on bullets to connect crimes to certain firearms (and potential suspects).

As a top microscope manufacturer, UNITRON understands the importance of precision and accuracy when investigating gun crimes. UNITRON designs and manufactures professional microscopes for use in forensic laboratories. If your lab needs a microscope, contact us for quotes on high-quality comparison forensic microscopes and microscope accessories from UNITRON today!