Ballistic evidence is a type of forensic evidence that is collected during a criminal investigation and used in a court of law. It is the forensic science dealing with firearms and firearm projectiles. Ballistics involves identifying specific marks a firearm makes on a bullet, the angle of trajectory which a bullet travels after being fired, and the damage a bullet causes when it strikes a surface. Ballistic evidence is used to identify the type of weapon that was used in the commission of a crime and other details of the crime, such as where the shooter was standing in relation to their target. It may also tell whether a weapon used in one crime has been used in the commission of another crime where identical ballistic evidence was discovered. Ballistic evidence is often used to reconstruct the events that transpired in the commission of a crime.
Forensic examiners can test-fire a suspect’s gun, then compare the marks on the crime scene bullet to marks on the test-fired bullet to determine if the bullets are likely to have been fired from the same gun or different guns. Cartridge cases are compared in the same way. Ballistic comparison is a relatively new technology that has been developed by a few companies. The two basic tools for ballistic investigations are the comparison microscope, which allows comparison and effective analysis of the evidence, and a software program that allows for the ballistic comparison using a system which stores the data and image base of firearms for further comparison in order to identify relationships between criminal acts.
Ballistic evidence is used to determine the type of weapon that was used in a crime, the location of a shooter, and whether or not the weapon used in one crime bears similar markers to evidence found in another crime. It can also help determine how a crime was committed. However, like fingerprint evidence, ballistic evidence has its limitations and can be discredited as "junk science" when it becomes apparent just how flawed the theories behind the science can be.
