The identification of bruises or abrasions usually in the shape of two semi-circles or brackets as a human bite mark made by a particular set of teeth is a function of forensic dentistry referred to as bite mark identification. This form of impression identification, also called forensic odontology, is based on the assumption that no two people in the world have front teeth that are identical in thickness, shape, relationship to each other and patterns of wear.
The process of comparing a bite mark to a known set of teeth is not unlike the identification of latent fingerprint, footwear and tire track impressions. Bite mark wounds are found on victims of murder, rape, and child molestation. This type of crime scene evidence is preserved by life-size photography, tooth mark tracings onto transparent sheets and dental casts of the impressions themselves. A suspect might be asked to bite down on a pliable surface for an impression sample, have a cast made of his teeth, or both. Usually, connecting a suspect to a victim through expert bite mark testimony will be enough evidence, by itself, to sustain a criminal conviction. For this reason bite mark evidence must be 100 percent reliable. Unfortunately it is not even close to that.
The field of bite mark identification exploded in the 1980s. Hundreds if not thousands of defendants went to prison on the strength of bite mark testimony. Although bite mark identification has been a recognized branch of forensic science since 1970, it was the 1979 trial of serial killer Ted Bundy in south Florida that put this form of identification on the map the way the O. J. Simpson murder case popularized DNA profiling in the mid-1990s.
The Ted Bundy Serial Murder Case
After killing 30 to 100 college-aged women in the states of Washington, Utah and Colorado, Theodore Bundy entered a Florida State University sorority house in Tallahassee where he sexually assaulted and murdered two Chi Omega sorority members. The police arrested him a short time later in a stolen car, then put him on trial for murder.
The prosecutor had plenty of nonphysical evidence against Mr. Bundy, but it was circumstantial and didn't place him in the Chi Omega murder room. The killer had left a hair follicle on a crime scene stocking mask that looked similar under a microscope to samples from Bundy's head. But hair identification wasn't enough by itself to carry a conviction. The rapist had left traces of semen, but these murders were committed more than ten years before the dawn of DNA analysis.
If the Dade County prosecutor had any chance of convicting Ted Bundy he would have to connect him to the murder scene through a bite mark wound on one of the victims. To do that the prosecutor called on Dr. Richard Souviron, the chief odontologist for the Miami-Dade County Medical Examiner's Office. He also enlisted the services of Dr. Lowell J. Levine, a forensic dentistry consultant to the New York City Medical Examiner's Office. To round out his battery of experts the prosecutor brought in Dr. Norman Sperber, an odontologist with the San Diego and Imperial County Medical Examiner's Office in California. These three forensic experts comprised the nation's most renowned bite mark analysts.
Dr. Souviron took the stand and testified that the sorority house attacker left a postmortem double-bite mark on one victim's left buttock. He had bitten once, turned sideways, them clamped down again. The killer's top bicuspids and his lateral and central incisors had remained in the same position, but he had made two wound brackets with his lower front teeth. When he photographed Ted Bundy's teeth Dr. Souviron noticed they were of uneven length, chipped and oddly aligned, factors that helped individualize the defendant's bite mark pattern. To illustrate for the jury that Mr. Bundy's teeth matched the murder scene wound, Dr. Sourviron laid a photograph of the defendant's teeth, depicted on a transparent sheet, over an enlarged photograph of the bite mark. The bottom edges of Bundy's teeth lined up perfectly with the crime scene wound.
Dr. Norman Sperber and Dr. Lowell Levine took the strand and lent their expertise to the identification. Bundy, representing himself, brought in his own dental expert, an odontologist from Maryland who testified that "the dental pattern [bite mark] is one I'd expect to find in 20 percent of the population of male Caucasians." The defense expert didn't say the bite mark on the victim couldn't have been Bundy's, he just wasn't willing to identify the wound as coming from the defendant to the exclusion of all others.
The jury found Ted Bundy guilty as charged. The judge sentenced him to death, and ten years later Ted Bundy was executed. Before his execution he confessed to the sorority house killings and dozens of other lust murders.
The Ted Bundy case established the credibility and usefulness of forensic bite mark analysis, and for a while placed it on the same level, in terms of reliability, as latent fingerprint identification. But following a series of high-profile misidentifications in bite mark cases, this form of impression analysis was no longer considered as reliable as latent fingerprint identification. Today, in most states, odontologists are not allowed, by law, to state unequivocally that a defendant is the source of a bite mark. The most these experts can say is that the questioned bite mark is consistent with having been made by the defendant's teeth.
The process of comparing a bite mark to a known set of teeth is not unlike the identification of latent fingerprint, footwear and tire track impressions. Bite mark wounds are found on victims of murder, rape, and child molestation. This type of crime scene evidence is preserved by life-size photography, tooth mark tracings onto transparent sheets and dental casts of the impressions themselves. A suspect might be asked to bite down on a pliable surface for an impression sample, have a cast made of his teeth, or both. Usually, connecting a suspect to a victim through expert bite mark testimony will be enough evidence, by itself, to sustain a criminal conviction. For this reason bite mark evidence must be 100 percent reliable. Unfortunately it is not even close to that.
The field of bite mark identification exploded in the 1980s. Hundreds if not thousands of defendants went to prison on the strength of bite mark testimony. Although bite mark identification has been a recognized branch of forensic science since 1970, it was the 1979 trial of serial killer Ted Bundy in south Florida that put this form of identification on the map the way the O. J. Simpson murder case popularized DNA profiling in the mid-1990s.
The Ted Bundy Serial Murder Case
After killing 30 to 100 college-aged women in the states of Washington, Utah and Colorado, Theodore Bundy entered a Florida State University sorority house in Tallahassee where he sexually assaulted and murdered two Chi Omega sorority members. The police arrested him a short time later in a stolen car, then put him on trial for murder.
The prosecutor had plenty of nonphysical evidence against Mr. Bundy, but it was circumstantial and didn't place him in the Chi Omega murder room. The killer had left a hair follicle on a crime scene stocking mask that looked similar under a microscope to samples from Bundy's head. But hair identification wasn't enough by itself to carry a conviction. The rapist had left traces of semen, but these murders were committed more than ten years before the dawn of DNA analysis.
If the Dade County prosecutor had any chance of convicting Ted Bundy he would have to connect him to the murder scene through a bite mark wound on one of the victims. To do that the prosecutor called on Dr. Richard Souviron, the chief odontologist for the Miami-Dade County Medical Examiner's Office. He also enlisted the services of Dr. Lowell J. Levine, a forensic dentistry consultant to the New York City Medical Examiner's Office. To round out his battery of experts the prosecutor brought in Dr. Norman Sperber, an odontologist with the San Diego and Imperial County Medical Examiner's Office in California. These three forensic experts comprised the nation's most renowned bite mark analysts.
Dr. Souviron took the stand and testified that the sorority house attacker left a postmortem double-bite mark on one victim's left buttock. He had bitten once, turned sideways, them clamped down again. The killer's top bicuspids and his lateral and central incisors had remained in the same position, but he had made two wound brackets with his lower front teeth. When he photographed Ted Bundy's teeth Dr. Souviron noticed they were of uneven length, chipped and oddly aligned, factors that helped individualize the defendant's bite mark pattern. To illustrate for the jury that Mr. Bundy's teeth matched the murder scene wound, Dr. Sourviron laid a photograph of the defendant's teeth, depicted on a transparent sheet, over an enlarged photograph of the bite mark. The bottom edges of Bundy's teeth lined up perfectly with the crime scene wound.
Dr. Norman Sperber and Dr. Lowell Levine took the strand and lent their expertise to the identification. Bundy, representing himself, brought in his own dental expert, an odontologist from Maryland who testified that "the dental pattern [bite mark] is one I'd expect to find in 20 percent of the population of male Caucasians." The defense expert didn't say the bite mark on the victim couldn't have been Bundy's, he just wasn't willing to identify the wound as coming from the defendant to the exclusion of all others.
The jury found Ted Bundy guilty as charged. The judge sentenced him to death, and ten years later Ted Bundy was executed. Before his execution he confessed to the sorority house killings and dozens of other lust murders.
The Ted Bundy case established the credibility and usefulness of forensic bite mark analysis, and for a while placed it on the same level, in terms of reliability, as latent fingerprint identification. But following a series of high-profile misidentifications in bite mark cases, this form of impression analysis was no longer considered as reliable as latent fingerprint identification. Today, in most states, odontologists are not allowed, by law, to state unequivocally that a defendant is the source of a bite mark. The most these experts can say is that the questioned bite mark is consistent with having been made by the defendant's teeth.
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