Gunshot wounds

DEFINITION: Wounds caused by projectiles fired from firearms.

SIGNIFICANCE: By analyzing the physical characteristics of gunshot wounds, forensic scientists can determine such elements of a crime as the shooter’s approximate distance from the victim at the time the gun was fired, the positions of the victim and the shooter, and the caliber or type of bullet.

Since the first treatise on gunshot wound forensics was published in France in 1857, the technologies used to analyze the wounds made by firearms have advanced a great deal. For example, the chemical analysis of gunshot residues on wounds and clothing has been increasingly displaced by more precise analysis using scanning electron microscopes. Simple tools still have their place, however; among these are the blunt probes used to track wound channels.

Forensic analysis of gunshot wounds is made much easier when emergency rooms take photographs and X-rays before surgery is performed on shooting victims. X-rays can reveal not only bullets or pellets that have not exited but also small lead fragments that can show a bullet’s path through the body (the wound channel). X-rays can also help an analyst determine the caliber of an embedded bullet.

During autopsies on shooting victims, many photographs are taken of the wounds. These are supplemented with detailed notes about the conditions of any skin, hair, and clothing around the wounds. Investigators may also supplement autopsy photographs and notes with additional information gleaned using technologies like high-speed ballistics photography. Ballistics experts can use high-speed cameras to gain valuable insight into how a gunshot wound was created by identifying and matching bullet trajectories, impact marks, and exit wounds.

Projectile Paths

The wound channel can reveal the angle, height, and distance from which a projectile was fired, allowing analysts to determine the locations and body postures of the shooter and the person who was shot. This information can support or debunk a claim of self-defense. Blood spatter patterns at the can also reveal a great deal about the positions of the shooter and the victim.

Often, a projectile shot from a firearm does not take a straight path from entry to exit; for example, it may be deflected by bones. bullets tend to make a straighter path through a body than rifle bullets because pistol bullets are generally shorter than rifle bullets. A bullet that enters a body after having ricocheted off some surface will usually penetrate less deeply and take a deviated path.

Shotgun pellets disperse in a regular conical pattern before they hit a target; the exact pattern depends on the type of gun, the ammunition, and the setting of the gun’s choke (which widens or narrows the dispersal pattern). Accordingly, the location of pellets in the victim’s body can indicate the distance from which the shotgun was fired. In the case of high-powered rifle bullets, the wound channel may reveal destruction not only from the bullet itself but also from the “temporary wound cavity” that rapidly expands and then contracts as the body absorbs the bullet’s energy.

Sequencing

When a victim has been shot multiple times, forensic scientists can determine the order in which the shots were fired by examining the wounds. According to “Puppe’s rule,” if the bone fracture lines from one shot are interrupted by fracture lines from another shot, the interrupted fracture occurred after the other fracture.

The cleanliness of the wounds offers additional information about the order of the shots. As a bullet travels down the barrel of a gun, it may get coated with sooty material; this sooty “bullet wipe” will be deposited on an entrance wound. Because the first bullet from a clean gun is cleaner than subsequent shots, the absence of a bullet wipe on a wound may indicate that the wound came from the first shot.

Entrance and Exit Wounds

The shape and other characteristics of an entrance wound can reveal much about the distance from which the gun was fired and the type of gun used. For example, a contact wound (from a gun placed on or very close to the skin) is more likely to be circular than a wound from a shot fired at a distance. A contact wound is more likely to show stellate (star-shaped) tearing than a distant shot, especially if the weapon used is a handgun.

A “shored” entry or exit wound reveals that the skin was reinforced by something else. Shoring may show, for example, that the victim was positioned with an arm in front of the chest, and the same bullet that entered and exited the arm then entered the chest. Shoring on an exit wound might reveal, for example, that the victim was lying on pavement.

The shape of the hole in the victim’s clothing may indicate the type of bullet (for example, pointed or hollow point), and gunpowder residue analysis can determine whether the muzzle was next to or very close to the victim’s body. Forensic examiners also look for scorching or blackening of the skin or clothing, for unburned or partially burned propellant particles, and (if an electron microscope is available) for metallic components of the primer (the device used to ignite the gunpowder). Charring on an entry wound is one of the signs that the gun’s muzzle was in contact with the victim’s skin. There may be evidence of the escaping gas from the burning gunpowder, such as bruising from a brief but violent ballooning of the skin. At “hard contact” range, the muzzle of the gun leaves an imprint on the skin.

At very close but nonadjacent distances, known as “near contact,” a gunshot will still leave forensically useful gas traces on the skin or clothing. If the projectile travels through the victim’s clothing, especially heavy clothing such as a leather jacket, the skin wound on the body may look very different from a wound in which the projectile struck the skin directly.

If a shotgun has been fired at close range, forensic experts are likely to find impact evidence from the wadding (a small petaled plastic cup that separates the pellets from the gunpowder). Because the wadding unfolds after exiting the barrel, the impression left by the wadding may provide good information about the distance between the shooter and the victim. Sometimes the wadding will be found in the victim.

Exit wounds are usually, but not always, larger than entry wounds, in part because some bullet points (hollow points) expand after impact. Hard-contact shots, however, can produce large entry wounds.

Bibliography

Dodd, Malcolm J. Terminal Ballistics: A Text and Atlas of Gunshot Wounds. CRC Press, 2006.

Haag, Lucien C. Shooting Incident Reconstruction. Academic Press, 2006.

Heard, Brian J. Handbook of Firearms and Ballistics: Examining and Interpreting Forensic Evidence. John Wiley & Sons, 1997.

Krywanczyk, Alison. "The Ins and Outs of Gunshot Wounds." Lablogatory, 22 Sept. 2023, labmedicineblog.com/2023/09/22/the-ins-and-outs-of-gunshot-wounds. Accessed 15 Aug. 2024.

Parker, Leroy. Workbook on Crime Scene Reconstruction of Shooting Incidents. Author House, 2005.

Phillips, Garrett. "Forensic Pathology of Firearm Wounds." Medscape, 30 Apr. 2024, emedicine.medscape.com/article/1975428-overview?form=fpf. 15 Aug. 2024.

Warlow, Tom. Firearms, the Law, and Forensic Ballistics. 3rd ed., CRC Press, 2012.