Friday, May 15, 2009

Bite Mark Evidence

Radley Balko has an article at Reason Magazine looking at bite mark evidence.  After his client was acquitted of murder, his defense attorney, Christopher Plourd, decided to administer an impromptu "proficiency exam" to a noted forensic dentist.
Plourd selected West because, even though the dentist was still active in the Mississippi and Louisiana courts, he had been suspended from the American Board of Forensic Odontology since the mid-1990s, and therefore might not be aware of the somewhat notorious Krone case. Plourd was right.

In October 2001, working for Plourd, a private investigator named James Rix sent West the decade-old photographs of the bite marks on Ancona's breast. Rix told West that the photos were from the three-year-old unsolved murder of a college student in Idaho. Rix then sent West a dental mold of his own teeth, but told him that they came from the chief suspect in the case. He also sent a check for $750, West's retainer fee.

Two months later, West sent Rix a letter and accompanying 20-minute video. In the video, West meticulously explains the methodology he uses to match bite marks to dental molds. Using the photo of Ancona's bitten breast and Rix's own dental mold, West then reaches the conclusion Plourd and Rix suspected he would: That the mold and the photos were a definite match.


Following the methodology that he has used in more than 100 other cases over the years, West confidently matches a dental mold and a photo of bite marks that have absolutely nothing to do with one another, decorating the fiction with the language of science. Though West is dead wrong, he sounds convincing, and it isn't difficult to imagine how he might prove persuasive to judges and juries.

In February, the National Academy of Sciences published a highly critical report about how forensic evidence is used and abused in the courtroom. The study was especially critical of bite-mark testimony, noting that it has contributed to a number of wrongful convictions over the years. The report concludes that there's simply "no evidence of an existing scientific basis for identifying an individual to the exclusion of all others" using bite-mark analysis. Yet bite-mark testimony is still common, and there are still plenty of people in prison as a direct result.

It would be nice to see more "proficiency tests" like Plourd's with West, only not just from defense attorneys. More importantly, the criminal justice system needs to act swiftly when "experts" like West are shown to conduct bogus examinations.

I've worked for the City of Los Angeles for a couple of decades now.  I've seen what our labs go through in order to meet regulatory requirements.  They receive test samples from the regulators, and have to come up with the right answer.  They are also subject to being given unmarked samples, not identified as coming from a regulator so they don't get automatic special treatment, and the analytical result had better match the known results of the samples.
A forensic analyst needs to be able to perform to that same standard before his or her work is accepted in a court of law.

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