For JANuary 2003 issue

SCIENCE IN CRIME DETECTION-112

Some Misconceptions in Gunshot Investigations

‑Dr. Anil Aggrawal

This time I am going to deal with some popular misconceptions in the field of gunshot investigation. Indeed there are many misconceptions held by all manner of people (including several laymen) concerning the trauma inflicted by firearms.

Many popular misconceptions are spread by popular crime novels, movies and TV serials. The result is that people are always asking me about them. Some misconceptions are encountered so frequently that special mention seems in order. Ten of the more significant misconceptions are discussed below.

THE PATH OF THE BULLET

One of the most prevalent misconceptions among lay people is that the bullet always travels in a straight line in the body, from the entrance to the exit wound, or wherever it came to rest in the body. This is not necessarily true. Here I may tell you about a phenomenon called ricochet. It is like a shuttlecock rebounding back from the opponent’s racket. Visualize the bullet as a shuttlecock.

Just as a shuttlecock can rebound off a racket, a bullet can rebound off a wall or roof. This is known as external ricochet. Similarly the bullet can bounce off bones within the body. This is known as internal ricochet. Since the phenomena of internal ricochet is well-known it is clear that the path of the bullet is not necessarily straight within the body.

Internal ricochet can and does occur. When it occurs, it usually results from the bullet striking bone and being deflected from its initial course into a second or a third course. This happens with frequency when the bullet strikes the head, penetrating the skull, allowing the bullet access to the curved inner portion of the skull where it may easily be turned from its original intracalvarial trajectory.

(Editor please reproduce figure 001.jpg here. Caption: FIGURE 1. Internal ricochet. A cross section of the fixed brain is shown. The bullet entered the lower left, proceeding upward and slightly toward the right, impacting the skull and ricocheting to the right and downward, and somewhat to the back. The bone fragments carried into the brain by the bullet indicate the inshoot area. This can in fact be another good additional point to differentiate between an entry and an exit wound.)

In addition, it is not unheard of for a bullet to strike a fascial plane (as found between two muscles) and to follow the fascial plane gliding along it to its exit from the body or to its final resting place.

Size of the entrance wound

When a bullet enters a body, it makes an entrance wound, and when it comes out it makes an exit wound. The rule of the thumb is that the entrance or inshoot wound is smaller than the exit or outshoot wound. But to say that it is ALWAYS so, is not correct. This is a popular misconception among the policemen, some forensic youngsters and even intelligent lay people who keep reading crime novels.

There is a variant of this misconception which may be stated thus: The entrance wound is always circular and neat, the exit wound is irregular in shape, has a jagged margin, and just looks different. In actuality, the inshoot wound may be larger than the outshoot wound and may be irregular in shape in contrast to the outshoot wound which may be circular and may even have an abraded margin. As an example, contrast a contact inshoot wound with a shored outshoot wound.

(Editor please reproduce figure 002.jpg here. Caption. FIGURE 2. Explosive contact and outshoot wounds contrasted. Two pairs are shown. The two panels on the right are of the explosive contact type. The panels on the left represent the outshoot wounds on the opposite side of the head.)

Also, consider a noncontact wound of entrance with a shored exit wound when the two wounds are similar in size and shape.

Destruction caused by semijacketed bullets

Semijacketed or hollow-point pistol or revolver bullets make “hamburger” out of the organs of the chest or abdomen. This misconception appears to have arisen from ignorance of wound ballistics and from confusion of the effects of velocity and bullet design. Semijacketed bullets have long been available for high-velocity rifles. Since the physician or surgeon treating the victim of firearms injury rarely knows the type of weapon employed, but is aware that a semijacketed bullet was recovered (by the surgeon himself), it is logical for him to assume that the massive destruction is due to the bullet, when in fact it resulted from the high velocity of the rifle employed.

To obtain cavitation and marked release of energy directed radially, the velocity of the missile must be higher than the highest achieved with a pistol or revolver bullet that leaves the muzzle, perhaps as high as 1600 to 1800 feet per second.

Semijacketed or hollow-point bullets leave the muzzle at a lower velocity (at speeds of 1500 feet per second or lower), when fired from most handguns. These bullets are designed to expand or mushroom. This causes a more rapid slowing of the bullet in the body and a more rapid transfer of kinetic energy to the tissues. Moreover, such a bullet is not as apt to perforate the body, passing through it, and maintaining a part of its kinetic energy as it exits. It is the more rapid and more complete transfer of kinetic energy that causes the greater “striking power” or “knockdown” capability of semijacketed and hollow-point bullets. Despite the mushrooming effect of these bullets and more rapid transfer of kinetic energy to the body, the visible wounding of tissues and organs cannot be distinguished from that caused by other varieties of bullets, provided that the velocity is maintained below approximately 1500 feet per second.

Direction of the bullet

This misconception appears quite logical in the first instance. In short, the misconception is that when the wound of entrance is higher on the body than the outshoot wound, it follows that the assailant was pointing the firearm slightly downward toward the victim at the moment of firing.

Although this appears to make sense, this is quite incorrect. The course of the bullet through the body has nothing to do with the relative positions of the victim and assailant. For example, the victim may have been leaning forward at the time of being shot. He may have been lying on the floor. He may have been climbing over a fence. This misconception is one frequently entertained by the attorney who, in the course of prosecution or defense of the accused, is anxious to establish a relationship between the victim and assailant that will fit the theoretic actions of the two. The most positive derivation that can be made is that the course of the missile in the body is consistent with the firearm being pointed slightly downward toward the victim at the time of discharge. There are many other relationships between the victim and the assailant and manner in which the weapon was held and pointed that are equally consistent. The number and details of such are limited only by the imagination of those anxious to reconstruct the situation at the time of the shooting.

Bullets are hot and sterile, or are they?

When the bullet emerges from the muzzle of the firearm, it is so hot that it will burn the skin. A variant of this misconception may be worded: The bullet is so hot that all bacteria upon it are killed and the missile is really a sterile object. Neither statement is true. The heat generated by the burning of the powder is intense, but the bullet is exposed to the heat for a very short period of time; moreover, only the base of the bullet is exposed. In addition, the friction generated by the rubbing of the bullet against the bore creates further heat. However, the specific heat and density of lead, the principal material used in bullet construction, combine to require much heat to increase the bullet temperature. Firearms examiners who recover bullets immediately after firing from test boxes filled with cotton waste find warm, perhaps even hot bullets. Nevertheless, the cotton waste is never scorched or burned by the bullet itself. Also, experimental firing has shown that bullets are not sterile after being fired from a firearm.

Abrasion collar

The bullet shot from a rifled firearm, spinning at a very high rate of speed, essentially drills its way into and through the target. This spinning motion or drilling is responsible, at least in part, for the abrasion ring seen in wounds of entrance. This statement is a half truth. There is no question but that the bullet is spinning. However, the rate of forward motion is so great that during the passage of a bullet through the thickness of the human chest or abdomen, it will make only one or two complete revolutions. The bullet does not “drill” its way through the body.

suicidal wounds

Many individuals die as a result of accidentally inflicted gunshot wounds sustained while cleaning a firearm. Actually, such accidents occur only rarely. Many times the gun-cleaning kit is at hand because the individual, bent on suicide, desires to make the investigating officials think that the wound was accidentally inflicted. Family members have been known to confuse the scene of death by the simple addition of a cleaning rod, oil, and patch. Sometimes the suicidal nature of the death is indicated by the contact type of wound in a position where accidental infliction would be nearly impossible.

right hand or the left hand?

Right-handed individuals commit suicide by holding the handgun in the right hand with the muzzle in contact with or close to the right temple. This is not the case. A moment’s reflection will reveal the error. The handgun may be held with either hand, and any finger may be used to actuate the trigger, although the forefinger and thumb are most frequently so employed. Many individuals are not familiar with firearms; they are especially apt not to hold the weapon in the expected, normal, or “proper” fashion.

determination of survival

It is possible to determine how long the victim survived following fatal injury from an examination of the wound. Unfortunately, this cannot be done. There are many factors which modify the survival time following mortal wounding. Natural disease processes can combine with trauma to shorten life. Alcohol and drugs may certainly contribute to a decrease in the length of survival. The environmental temperature, humidity, and other factors may affect survival. The extent of the wounding is very important, of course, but it cannot always be determined from an external examination of the body. In fact, it may be difficult to determine, even with a thorough autopsy.

autopsy on a firearm victim

It is a simple procedure to perform an autopsy upon the victim of a firearm injury. All that is necessary is to find the wounds of entrance and exit, locate the bullet, and point out the traumatized tissues and organs. This statement is obviously untrue. It is usually called the king of all misconceptions regarding firearms.

These are the common misconceptions people have while reading detective novels, and seeing crime movies. If they keep in mind these basic facts, they will be able to enjoy their crime reading much more.

This article has (1913) words

Dr. Anil Aggrawal, M.D.

Professor of Forensic Medicine

Maulana Azad Medical College

New Delhi‑110002