Forensic Science: How Does a Medical Examiner Differentiate Between an Entry Wound and an Exit Wound?
Whenever a shooting occurs and the police are called to investigate a dead body as a result of the shooting, Crime Scene Investigators (CSIs) will come to process the scene. The medical examiner will then determine where the bullet entered; if possible, where did it come from; and what caliber of bullet, or bullet diameter, was used to kill the victim.
In this article I will define what entrance and exit wounds are and what are the characteristics that make up an entry hole.
When a bullet enters a person, it leaves behind what is called a entry wound. However, that bullet will not necessarily leave another hole called exit wound when the bullet leaves the body. Many times, the bullet remains inside the victim’s body. When evaluating gunshot wounds, a medical examiner looks for entry and exit wounds and tries to find any bullets that are still lodged within the victim. Although the distinction is not always obvious, the medical examiner also tries to determine the difference between entry and exit wounds, because doing so can be crucial in reconstructing a crime scene. Knowing the trajectory or trajectory of a bullet can incriminate or exculpate suspects or help determine which projectile caused the fatal injury.
The characteristics of a gunshot wound depend on several factors:
- The distance between the muzzle, or end of a gun barrel, of the gun and the victim.
- The caliber, or diameter, and velocity of the bullet.
- The angle at which the projectile enters the body.
- If the bullet stays inside the victim or goes through, it leaves or exits the body. Hence the term, side to side gunshot wound.
A medical examiner can determine the distance from which a single projectile was fired by closely examining the entry point of the bullet. The characteristics of these entries are the following:
- If the muzzle was two (2) or more feet away from the victim, the entry wound is usually a small hole, accompanied by a abrasion neck. An abrasion collar is a blue-black bruise effect in a halo surrounding the entry wound. Some black soot may remain on the skin as the skin literally wipes away the bullet as it passes through the entry wound into the victim.
- If the mouth was between six (6) inches and two (2) feet from the point of entry, the skin may have a tattooed, or spotted, appearance. This tattooed appearance is the result when tiny particles of gunpowder discharged from the muzzle embed themselves in the skin, producing tiny red dots of blood within the skin in a mottled pattern around the wound.
- If the muzzle was less than six (6) inches from the victim, the shot produces a hole, a small area of smearing, a surrounding area of charring, and a bright red color to the wounded tissue.
- If the barrel is pressed against the victim when the gun is fired, the hot gases and minute particles are driven directly into the skin, causing further charring and tearing the skin in a star shape, or starrypattern.
In general, exit wounds tend to be larger than entry wounds due to the fact that the bullet cuts or tears soft tissue as it travels up and out through the skin. The size and shape of the exit wound depends on the caliber, velocity, and shape of the bullet. For example, soft lead bullets are easily deformed as they enter and pass through the body, especially if they hit any bony structures along the way. When that happens, the bullet can become severely deformed, which, in turn, causes more extensive tissue damage in its path, often resulting in a gaping, jagged exit wound.
Determining the difference between entry wounds and exit wounds is not always simple for the medical examiner, especially when the exit wound is propped up. propped up refers to when clothing or some other material provides support to the wound. The jagged attribute of many exit wounds is caused by the bullet working its way through the skin. However, if the victim’s skin is supported by tight clothing or if the victim is against a wall or other structure, the skin is less likely to break. Therefore, the exit wound will be smaller and less irregular. It will take on the likeness of an entry wound.
next time you look NCIS or your favorite CSI television show, you will become more familiar with the terminology used when criminalists investigate a gunshot victim.
