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Dr. L. Thomas Johnson
Potential Bite-Mark Database Causes Concern
by
Josh Katz
Researchers at Marquette University announced the creation of a computer program to decipher bite-mark characteristics, stoking debate about the admissibility of such evidence.
30-Second Summary
The researchers hope the new technology will be a step toward the formation of a bite-mark database, which would help authorities identify perpetrators in criminal cases.
Dr. L. Thomas Johnson and his team compiled 419 bite impressions from soldier volunteers in Wisconsin for the study. Johnson is planning to gather more samples throughout the country “to expand the database into something close to law enforcement's DNA databanks,” the Associated Press reports.
Bite marks have been used to convict suspected criminals for 40 years. In one of the most famous examples, serial killer Ted Bundy was found guilty of murdering a Florida State University student in 1978 after evidence linked his dental impression to bite marks on the victim’s body.
However, critics say bite-mark testimony is unreliable, and the creation of a database would not change that. Dr. Mike Bowers, a deputy medical examiner in California, called Johnson’s study “scientifically illiterate."
The Innocence Project blames bite-mark testimony on the false convictions of numerous individuals who were later exonerated by DNA evidence. The project cites a study indicating a “63.5% rate of false identifications.”
Opponents to such evidence argue that human skin can distort bite marks, teeth can change over time, and the matter can become highly subjective. But many agree that bite marks can be “helpful in excluding someone as a suspect, or determining that the suspect could be the one who inflicted the bite,” according to The New York Times.
Dr. L. Thomas Johnson and his team compiled 419 bite impressions from soldier volunteers in Wisconsin for the study. Johnson is planning to gather more samples throughout the country “to expand the database into something close to law enforcement's DNA databanks,” the Associated Press reports.
Bite marks have been used to convict suspected criminals for 40 years. In one of the most famous examples, serial killer Ted Bundy was found guilty of murdering a Florida State University student in 1978 after evidence linked his dental impression to bite marks on the victim’s body.
However, critics say bite-mark testimony is unreliable, and the creation of a database would not change that. Dr. Mike Bowers, a deputy medical examiner in California, called Johnson’s study “scientifically illiterate."
The Innocence Project blames bite-mark testimony on the false convictions of numerous individuals who were later exonerated by DNA evidence. The project cites a study indicating a “63.5% rate of false identifications.”
Opponents to such evidence argue that human skin can distort bite marks, teeth can change over time, and the matter can become highly subjective. But many agree that bite marks can be “helpful in excluding someone as a suspect, or determining that the suspect could be the one who inflicted the bite,” according to The New York Times.
Headline Link: ‘Scientists Are Building Database of Bite Marks’
The Marquette University researchers hope that the bite-mark database will be useful tool for authorities. They “built a computer program to catalog characteristics, including tooth widths, missing teeth and spaces between teeth. The program then calculated how frequently—or infrequently—each characteristic appeared,” according to the Associated Press.
Source: Associated Press
Background: Controversial bite-mark testimony
Forensic Dentistry Online explains the science behind bite marks and the controversy over its use as admissible evidence: “Currently, there is no agreement among forensic odontologists about the individuality (uniqueness) of the dentition or the behaviour of human skin during biting.”
Source: Forensic Dentistry Online
In 1992, Ray Krone was convicted of murdering a Phoenix bartender, thanks in large part to bite-mark testimony. Nicknamed the “Snaggletooth Killer” because of his irregular teeth, Krone was freed in 2002 when DNA evidence from the case pointed to another man. In regard to the validity of bite-mark testimony, Krone said, “It's hard for me to believe that any computer can be that accurate … can discern the minute distinctions."
Source: York Daily Record
Perhaps one of the most famous cases utilizing bite-mark testimony involved the conviction of serial killer Ted Bundy. Bundy left bite marks on the buttocks of one of his victims, Lisa Levy. The prosecution was able to prove that the bite marks matched Bundy’s teeth, marking the “first case in Florida's legal history that relied on bite-mark testimony.” Court TV Crime Library describes the Bundy case and a number of other cases involving bite-mark evidence.
Source: Court TV Crime Library
A New York Times article from January 2007 explains that bite-mark cases have a history of unreliability. A 1999 study by the American Board of Forensic Odontology found that the technique failed 63 percent of the time. According to the Times, “Lawyers, for their part, are taking steps to counter what they call the ‘C.S.I. effect,’ when juries become overly impressed by forensic evidence.”
Source: The New York Times
Opinion & Analysis: ‘Cases Where DNA Revealed that Bite Mark Analysis Led to Wrongful Arrests and Convictions’
The Innocence Project writes, “Bite mark analysis is particularly troubling because of the almost complete absence of validated rules, regulations, or processes for accreditation that establish standards for experts or the testimony they provide.” The Innocence Project describes five cases where DNA evidence exonerated individuals who had previously been convicted because of bite marks.
Source: Innocence Project
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