At Least Two Dozen People Have Been Falsely Convicted Thanks to “Bite Mark Analysis”

A blog about murder, theft, and other wickedness.
June 17 2013 5:39 PM

At Least Two Dozen People Have Been Falsely Convicted Thanks to “Bite Mark Analysis”

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A dentist holds up the plaster cast of a patient's set of teeth.

Photo Illustration by Sean Gallup/Getty Images

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The Associated Press moved a tremendous story Sunday about bite mark analysis, an odd and discredited branch of forensic dentistry that, over the past few decades, has been used to convict numerous criminal defendants, many of whom are likely not guilty. Later this month, the AP reports, a New York judge may deliver a ruling that could permanently bar bite mark analysis as evidence in criminal cases. It’s a ruling that’s long overdue.

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What is bite mark analysis, you ask? Basically, it’s based on the idea that bite marks, like fingerprints, can be definitively traced back to specific individuals. An analyst will study a bite, match it back to a particular set of teeth, and testify that those were the only teeth in the whole wide world that could’ve delivered that particular bite. AP reporter Amanda Lee Myers writes that modern bite mark analysis “began in 1954 with a piece of cheese in small-town Texas. A dentist testified that a bite mark in the cheese, left behind in a grocery store that had been robbed, matched the teeth of a drunken man found with 13 stolen silver dollars. The man was convicted.” In 1979 bite mark analysis was used to link serial killer Ted Bundy to the murder of Lisa Levy, who had been bitten on her left buttock.

The Bundy case made bite mark analysis famous. And though Bundy was extremely guilty, in general the science of biting is, well, bollocks. As the AP notes, “there is no scientific proof that teeth can be matched definitively to a bite into human skin.” The certification process for bite mark analysts isn’t very rigorous, and there are almost never any penalties for getting a case wrong:

Only one member of the American Board of Forensic Odontology has ever been suspended, none has ever been decertified, and some dentists still on the board have been involved in some of the most high-profile and egregious exonerations on record.

The AP found that, since 2000, at least two dozen people have been freed after DNA testing and other methods cleared them of the crimes that bite mark analysts claimed they committed. Myers writes about Ray Krone, the "Snaggletooth Killer," who was convicted of the same murder twice based on the testimony of a forensic dentist who claimed that Krone was responsible for bite marks left on the victim. In 2002 Krone was exonerated from death row thanks to DNA testing. The bite mark analyst has never been held accountable.

"You're dumbfounded," Krone said in a telephone interview from his home in Newport, Tenn. "There's one person that knows for sure and that was me. And he's so pompously, so arrogantly and so confidently stating that, beyond a shadow of doubt, he's positive it was my teeth. It was so ridiculous."

All of this reminded me of Cameron Todd Willingham, the Texas man who was the subject of a great profile by the New Yorker’s David Grann a few years back. Willingham was executed in 2004 after being convicted of setting a fire that killed his three children, largely thanks to testimony from arson investigators who claimed that “burn patterns” and “puddle configurations” proved conclusively that Willingham set the fire on purpose. But Grann’s piece makes clear that there was no basis for the investigators’ conclusions, and that Willingham almost certainly did not commit the crime for which he was put to death.

We’ve been convicting people based on pseudoscience for a long, long time in this country. While I’ve written about the numerous problems with modern DNA analysis labs, stories like these are good reminders that forensic science has made significant progress in recent years. And once we get rid of bite mark analysis, it will be even better.

Justin Peters is a writer for Slate. He is working on a book about Aaron Swartz, copyright, and the rise of “free culture.” Email him at justintrevett@fastmail.fm.