A forensic dentist who helped identify victims of the cannibalistic Milwaukee serial killer Jeffrey Dahmer and whose work has been criticized by other forensic experts is helping researchers at Marquette University build a computer program to measure and catalog bite mark characteristics and their frequency. While bite marks are sometimes used in court, the discipline has been widely discredited and is not a validated science.
Dr. L. Thomas Johnson is collecting dental impressions from around the country to build a massive database. The software would then attempt to calculate how rarely a particular dental characteristic shows up in the population.
[Dr. Johnson] acknowledged that his software will probably never turn bite-mark analysis into a surefire identifier like DNA and that he would need tens of thousands of samples before his work would stand up in court.
Nevertheless, Dr. Johnson maintains the database will lend scientific credibility to bite-mark testimony in criminal trials based on the belief that every person’s tooth impression is unique. But human skin can change and distort bite impressions and other experts, including Dr. Mike Bowers, a deputy medical examiner in Ventura County, Calif., and a member of the American Board of Forensic Odontology, consider it sham science.
"… It's not science," said Peter Neufeld, co-director of the Innocence Project, which works to free wrongfully convicted inmates.
Since 2000, at least seven people in five states who were convicted largely on bite-mark identification have been exonerated, according to the Innocence Project.
In Arizona, Ray Krone was found guilty in 1992 of killing a Phoenix bartender based largely on expert testimony that his teeth matched bites on the victim. He was sentenced to death, won a new trial on procedural grounds, was convicted again and got life. But DNA testing in 2002 proved he wasn't the killer. Krone was freed and won a spot on the ABC reality show "Extreme Makeover" to remake his teeth.
In Mississippi, forensic odontologist Dr. Michael West has come under fire after he testified in two child rape-murders in the 1990s that bite marks positively identified each killer. Kennedy Brewer was sentenced to death in one case, and Levon Brooks got life in prison in the other.
DNA tests later connected a third man to one of the rapes, and investigators say he confessed to both murders. In Brewer's case, a panel of experts concluded that the bites on the victim probably came from insects. Brewer and Brooks were exonerated earlier this year.
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(Associated Press, 5/14/08)
While bite mark analysis may be the most notorious of the dubious techniques that are cloaked in science when introduced in court, there are several scientific disciplines that are not validated and have contributed to wrongful convictions.
Read more about unreliable and limited scientific techniques.