06 May 2014

10 Things to know about ballistics

Ballistics experts can tell from where, how often, and sometimes by whom a gun was fired in a crime. Here’s how they do it.

Ballistic evidence, both from ballistic experts from the prosecution and the defence, is crucial in determining what exactly happened on the day Reeva Steenkamp was shot four times with a 9mm pistol by Oscar Pistorius.

Just as in the case of something such as blood spatter analysis, much can be determined about a crime scene by looking at bullet remainders, shell casings and angle of entry wounds.

The word ‘ballistics’ comes from the Latin ballista which is refers to an ancient military machine for throwing stones.

Ballistics means the “art of throwing; the science of projectiles”.

Read: What we know about Reeva's injuries

But what exactly does a ballistics expert do, and what are the things they look for?

• Ballistics experts mostly work with crime scenes and are forensic specialists who collect, study and analyse all evidence available that is related to ammunition and firearms.

• Ballistics experts can usually identify the type of firearm that was used in a crime, where it was fired from and also how many bullets were fired.

• The type of firearm used in a crime can usually be identified by the bullet (if it can be found) or by the casings left at the scene.

• Every firearm leaves a unique set of markings on a bullet fired from that weapon. These markings are called striations. These are unique to every weapon, as are fingerprints to humans.

• If a weapon, suspected of being used in a crime, is recovered, ballistic experts can fire that weapon in a special laboratory, and compare the striations to those on the bullet from the crime scene. If there is a match, they can positively identify the weapon used in the crime.

Read: What happens to the body when you are shot

• The probable distance and angle of the gunshot can also be determined – a very important issue in the Pistorius case, as he claims he was not wearing his prosthetic legs when he fired four shots through the bathroom door. His defence team has used this to try and prove that there was no premeditation.

If he had been wearing his prostheses, the trajectory of the bullets would have been different. Captain Christian Mangena, police ballistics expert, also testified that the shots were fired from between 0,6 – 3m away, which supports claims made by Pistorius.

• External ballistics is the study of the trajectory of the projectile after it leaves the shooting device. Many things can influence this, such as gravity, weather conditions (if the gun has been fired outdoors) or air drag.

• Terminal ballistics refer to the study of a projectile when it hits its target: the angle and depth of the entry wound can tell ballistics experts much about a shooting incident.

• Forensic experts can also test for gunshot residue on the hands of a suspect. These particles are emitted from the back and from the muzzle of the gun when it is fired. This residue, which cannot be removed with normal hand washing, often contain the elements antimony, lead, barium, and sometimes titanium and zinc.

• A lack of gunshot residue on the hands of someone who supposedly committed suicide would indicate a likely murder to ballistic and forensic experts.

Read more:

7 Ways forensic scientists identify bodies
Why we need more psychoanalysis in the courtroom
Has the break helped or hindered Oscar's case?

Sources: Online Etymology Dictionary;; crime-scene-investigator-network;
Image: bullet from Shutterstock


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