Crime Library: Criminal Minds and Methods

Ballistics: The Science of Guns

The Magic Bullet

It's not impossible for a bullet to behave erratically, and that awareness influences trajectory studies, as well as bloodstain pattern analysis. In one Oklahoma case, as reported by Innes, a bank robber put a .357 Magnum to the back of the head of a female witness and fired. The bullet entered her skull, made a sharp turn, went around inside her head and exited out the forehead. The girl was knocked unconscious but she recovered and testified against him. In another case, a .22 caliber bullet entered a vein at the wrist, a seemingly innocuous wound, but it traveled inexplicably up the arm and right into the heart, killing the person.

When faced with bullet wound cases, forensic pathologists must make determinations about where the bullet entered a body and if and where it exited. (For inorganic substances, trajectory studies involve lasers and calculus, as well as computerized simulations that include ricochet effects.) Often, it's difficult in human tissue to know which wound is entrance and which is exit, but there are some telltale signs.

According to, bullet entrance holes "typically have very even margins." If the gun muzzle made no contact with the clothing, the hole through most materials will be smaller than the bullet. There may also be gunshot residue present if the gun was shot at close enough range, and sometimes one can tell from the blood spatter pattern near the body.

Book cover: A. Y. Wonder's Blood Dynamics
Book cover: A. Y.
Wonder's Blood

A.Y. Wonder, in Blood Dynamics, says that "Impact spatter patterns resulting from gunshot are combinations of contact between an exposed blood source, the bullet, and gas components." The entrance wound involves a missile, or bullet, and the exit may be the missile or fragments of it. The bullet may open up a wound or strike blood that's already there from a previous wound, such as when someone is shot more than once. If the target person is in motion, especially rapid motion, the gas and missile may strike different areas and make identification of an entrance wound more complicated. The condition of the wound has to be analyzed fully before any conclusions can be drawn.

High velocity bullets are often equated in formulaic evaluations with a "mist" pattern, which means the blood droplets are finer and create a lighter pattern. However, Wonder points out, mist is often not about the bullet's speed, and mist also results from other wound-causing incidents, so one should not identify gunshot solely in terms of spatter size or quality. The properties of the gun must also be considered, as well as the angle of the shooting and whether or not the victim was in motion of any kind—running, struggling, falling, riding in a car.

Book cover: Practical Homicide Investigation
Book cover: Prac-
tical Homicide

Vernon J. Geberth, in Practical Homicide Investigation, says that entrance wounds are generally smaller than exit wounds and have an "abrasion collar" where the skin was forced inward, and a gray or black ring around the edge. However, if the bullet hits an obstruction before entering, it may enter in fragments. Exit wounds are often ragged in appearance, and can have shreds of tissue extruding outward (but not always). To some extent, identification will depend on the condition of the body, but there may be some evidence of more blood escaping through the exit wound. If the gun is held against the skin, creating a contact wound, that makes for easier identification of where the bullet entered.

Of course, not all bullets actually exit. They may not have sufficient velocity or a bone may deflect them, possibly causing them to travel under the skin and all around the body in unpredictable ways.

Michael Baden (CORBIS)
Michael Baden

Former New York City medical examiner, Michael Baden, agreed to serve on Congressional Select Committee on Assassinations in 1977, and he recruited eight other medical examiners to assist. Their assignment was to go over the records from the autopsy for the November 22, 1963, assassination of John F. Kennedy and evaluate the findings. One goal was to put to rest the many diverse theories that there were more shooters than just the one the police quickly arrested, Lee Harvey Oswald.

Lee Harvey Oswald, mugshot
Lee Harvey Oswald,

President Kennedy was shot in Dallas, Texas, while riding with his wife in the backseat of an open-top car before a large crowd of admirers. One bullet also wounded Governor John Connally, who was in the front seat. The dying Kennedy was rushed to Dallas's Parkland Hospital, but then the FBI illegally transported him to Bethesda Naval Hospital in Washington. Unfortunately, as Baden discovered, even a case as significant as this one can be mishandled by untrained people. None of the doctors who worked on the body were trained in forensic pathology, so they did not know how to trace bullet trajectory paths in human tissue. In addition, the Warren Commission, which was set up in 1964 to dispel rumors of conspiracies, failed to interview pathologists with experience in gunshot wounds.

John F. Kennedy and the motorcade (AP)
John F. Kennedy and the
motorcade (AP)

As Baden's team looked further into the incident to see what could be determined, Baden noted what he described as a "forensic disaster." He contends that if the autopsy procedure had been done correctly, the many conspiracy theories would never have gotten off the ground.

Yet as it turned out, Commander James J. Humes, the pathologist who performed the autopsy, had been instructed not to perform a complete autopsy, but only to find the bullet, which was believed to still be lodged in the body. Try as he might, he couldn't find it. In his subsequent reports, his medical descriptions were nonexistent, and he basically referred interested parties to the photos, which were also badly done by an inexperienced photographer. Humes didn't even turn Kennedy over to look at the wound in the back of his neck, or call the receiving hospital in Dallas until too late to discover that a tracheostomy had been performed there, which he'd have found (if he'd looked) going right through the exit wound in the throat. He erroneously assumed the bullet had fallen out the same hole it had entered. He also failed to shave the head wound to see it clearly, and it was photographed through the hair. In addition, Humes miscalculated the wound's location by an error of four inches. With all of these mistakes, it would be impossible to make accurate determinations about bullet trajectories.

After only two hours (a very short time for an autopsy, especially on someone of such stature), he prepared the body for embalming. Then, because his notes were stained with blood, he burned them. After he found out about the procedure done in Dallas, he rewrote his notes based on what he recalled and what he could figure out. He ended up including material he himself never saw and failing to track the bullets properly. Thus, his report was filled with errors, which put Baden's team at a serious disadvantage.

They looked at the blurry crime scene and autopsy photographs, Kennedy's clothing, autopsy reports, and X-rays. It soon became clear that the people in charge had not realized the difference between an exit and entrance wound, and therefore they could not pinpoint the bullet's origin. They also couldn't tell how many shots had been fired.

Governor John Connally (AP)
Governor John
Connally (AP)

Then Baden realized that Kennedy's brain was missing, along with slides of tissues, so they had to rely on the clothing. The team managed to piece together the fact that two bullets had entered Kennedy. There was a small hole in the back of Kennedy's shirt and jacket, and small exit holes going through his shirt collar and tie. That was the bullet that had pierced his throat and gone into Governor Connally. It had fallen out of Connally's leg while he was on a stretcher. Years later, the governor showed Baden his entrance wound and it was found that the bullet had been moving sideways, which helped to calculate its actual trajectory. The other bullet had gone through the back of Kennedy's head and out over his right eye, ending up hitting a post on the car's windshield and falling to the floor. Both had come from behind.

After that, they wrote a two-volume report. "One of the recommendations we made," says Baden, "was that there should be some national attention paid to improving death investigation in this country. Part of the problem with that case was that the investigation was poorly done. The people who did the autopsy were not qualified to do it, and a poor autopsy can be misleading. Having a hospital pathologist who trained in natural diseases do an autopsy on President Kennedy is like having a general surgeon doing brain surgery. There are different kinds of expertise, and those doctors made lots of mistakes, such as creating false descriptions for why they couldn't find the bullet. They said it and they were wrong, and it lives with us even today."

Today, bullet trajectories are often mapped, calculated and run through a computerized simulation to aid in reconstruction. This has been a controversial tool, but it's also been helpful in difficult cases. Whether it was positive or negative in the following case depends on one's perspective.

We're Following
Slender Man stabbing, Waukesha, Wisconsin
Gilberto Valle 'Cannibal Cop'