How the Flawed Science of Bite Mark Analysis Put an Innocent Man behind Bars

An article in the Intercept takes a detailed look at the flawed science of bite mark analysis and the case of Bill Richards, a California man who was convicted in 1997 of murdering his wife, Pamela. Richards’ conviction was primarily based on the testimony of forensic odontologist Dr. Norman Sperber, who concluded that a photograph of a possible bite mark on Pamela’s hand specifically matched Richards’ dentition. According to the Intercept, not only did Sperber claim that Richards’ teeth matched the mark, but he also testified that only “one or two or less” out of 100 people would have such unique dentition. Dr. Greg Golden, an odontologist called by the defense, also testified and eventually agreed with Sperber’s conclusion that only about two percent of the population would have similar dentition.

Years later, both Dr. Sperber and Dr. Golden recanted their testimonies, writes the Intercept. Golden said that the mark was “just as likely” made by one of Richards’ dogs, and Sperber admitted that the photo evidence was too distorted to make an accurate comparison and that his statement about the uniqueness of Richards’ dentition was not grounded in any prior scientific research.

In 2001, Richards’ case was taken up by the California Innocence Project which filed a writ of habeas corpus in 2007 and won an evidentiary hearing in which a judge ruled that Richards’ conviction should be vacated. However, the Intercept writes that in 2010, that ruling was reversed on appeal, and the reversal was then upheld in 2012 by the California Supreme Court. The court’s controversial ruling essentially concluded that the testimony of a forensic expert could never be either true or false. The court’s justification for its ruling was that if experts were allowed to recant their trial opinions, an inordinate number of defendants would try to challenge their convictions and the finality of justice within the system would be jeopardized.

As numerous cases like Richards’ have emerged over the years, some odontologists have spoken out against the credibility of bite mark analysis and have received incredible backlash from the larger forensic odontology community. Exposing bite mark analysis as junk science jeopardizes forensic odontologists’ professions, yet the effort to protect the profession itself above its mission to seek criminal justice has been baffling.

According to the Intercept, at the 2015 American Academy of Forensic Sciences conference in Orlando, the inconsistency of forensic odontology could be seen even in American Board of Forensic Odontology (ABFO) members’ response to criticism of their professional practice. ABFO members designed a “decision tree” which was intended to guide bite mark analysis, starting with the simple question: Is this a bite mark? One-hundred case studies were reviewed by 39 ABFO bite mark analysts, only four of which garnered a unanimous decision. One odontologist said, “If you can’t train somebody with appropriate experience and qualifications [how to identify a bite mark] then it’s magic. And, you know, that’s not forensic science.”

Last year, California became the second state to codify a junk science statute, known in California as the Bill Richards Bill. The law allows for appeals based on “repudiated” expert opinions or on evidence “undermined by later scientific research or technological advances,” writes the Intercept. In light of the new law, Richards has another chance to appeal his conviction with the California Supreme Court where his case is currently pending.

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