Forensic Science - How Does a Medical Examiner Differentiate Between an Entrance and Exit Wound?

Whenever a shooting occurs and police are called tothe entrance wound.
investigate a dead body as a result of the shooting,- If the muzzle was between six (6) inches and two
crime scene investigators (CSI's) will come to process(2) feet from the point of entry, the skin may have
the scene. The medical examiner will then determinea tattooed, or spotted, appearance. This tattooed
where the bullet entered; if possible, where it exited;appearance is the result when tiny particles of
and what caliber bullet, or bullet diameter, was usedgunpowder discharged from the muzzle embed
to kill the victim.themselves in the skin, producing tiny red dots of
In this article, I will define what entry and exitblood inside the skin in a speckled pattern around the
wounds are and what the characteristics are thatwound.
make up an entry wound.- If the muzzle was less than six (6) inches from the
When a bullet enters a person, it leaves behind whatvictim, the gunshot produces a hole, a small area of
is called an entry wound. However, that bullet will notspotting, an encircling area of charring, and a bright
necessarily leave another hole called an exit woundred color to the wounded tissues.
when the bullet exits the body. Often times, the- If the muzzle is pressed against the victim when
bullet stays inside the victim's body. When evaluatingthe gun is discharged, hot gases and tiny particles are
gunshot wounds, a medical examiner looks for entrydriven right into the skin, producing greater charring
and exit wounds and tries to find any bullets stilland ripping the skin in a star-like, or stellate, pattern.
lodged inside the victim. Even though the distinction isIn general, exit wounds typically are larger in size than
not always evident, the medical examiner also triesentry wounds because of the fact that the bullet
to determine the difference between entry and exitcuts or tears the soft tissues as it forces its way up
wounds, because doing so can be crucial in rebuildingand out through the skin. The size and shape of the
the scene of a crime. Knowing the trajectory, orexit wound depend on the caliber, speed, and shape
path, of a bullet can incriminate or exculpate suspectsof the bullet. For example, soft lead bullets are easily
or help determine which projectile caused the mortalmisshapened as they enter and pass through the
wound.body, especially if they hit any bony structures along
The characteristics of a bullet wound are a functionthe way. When that occurs, the bullet may became
of several factors:grossly deformed, which, in turn, produces more
- The distance between the muzzle, or end of aextensive tissue damage in its wake and many times
gun's barrel, of the gun and the victim.results in an irregular, gaping exit wound.
- The caliber, or diameter, and velocity of the bullet.Determining the difference between entry wounds
- The angle at which the projectile enters the body.and exit wounds is not always simple for the medical
- Whether the bullet stays inside the victim or passesexaminer, especially when the exit wound is shored.
through, leaving, or exiting, the body. Hence theShored refers to when clothing or some other
term, through-and-through gunshot wound.material provides support to the wound. The ragged
A medical examiner can determine the distance fromattribute of many exit wounds is caused by the bullet
which a single projectile was fired by examiningtearing its way through the skin. However, if the
closely the bullet's point of entry. The characteristicsvictim's skin is supported by tight clothing or the
of those entries are as follows:victim is against a wall or other structure, the skin is
- If the muzzle was two (2) or more feet awayless likely to tear. The exit wound therefore will be
from the victim, the entrance wound ordinarily is asmaller and less ragged. It will take on the
small hole, accompanied by an abrasion collar. Anresemblance of an entry wound.
abrasion collar is a blue-black bruising effect in a haloThe next time you watch NCIS or your favorite CSI
surrounding the entrance wound. Some black sootTV program, you will be better knowledgeable about
may be left behind on the skin when the skin literallythe terminologies used when criminalists investigate a
wipes the bullet clean as it passes into the victim atgunshot victim.