At least 24 individuals charged or convicted, of murder or rape, based at least in part on identifying bite marks on the flesh of victims have been exonerated since 2000, according to the Innocence Project. Many of those individuals spent time behind bars.
A small group of dentists belonging to the American Society of Forensic Odontologists
are responsible for the proliferation of bite mark analysis. Those dentists’ findings are often key evidence in prosecutions — even though there is no scientific proof that teeth can be matched definitively to a bite into human skin.
The FBI doesn’t use it, and the American Dental Association does not recognize it. Now The Washington Post is sounding the alarm in an in-depth four-part series on the legitimacy of bite-mark analysis.
“Bite-mark evidence is the poster child for unreliable forensic science,” Chris Fabricant, director of strategic litigation at the New York-based Innocence Project told The Associated Press. According to the Post, there are hundreds of people in prison due to bite-mark testimony, including at least 15 on death row.
In 2009, a National Academy of Sciences report on the state of forensic science in courtroom across the country was highly critical of a wide range of forensic specialties, from fingerprints to hair and fiber analysis to blood spatter and bite marks.
Bite-mark analysts look at indentations found in human skin thought to be caused by human teeth. According to the Post, analysts first confirm the marks are actually a human bite. They then compare those marks to plaster molds taken of the teeth of one or more suspects.
The NAS report was particularly critical of that process. The report found that there is “no science on the reproducibility of the different methods of analysis” of bite marks. The report concluded, “Different experts provide widely different results.”
One notable case of faulty bite-mark analysis involved a Pennsylvania native convicted in Ray Krone, the so-called “Snaggletooth Killer,” was convicted in 1992. After winning a new trial, he was convicted again in 1996 of the murder of a Phoenix woman.
Krone’s conviction was based principally on bite-mark identification. He was exonerated in 2002 after spending 10 years in prison (three of which were spent on death row).
In 2004, I participated in a forum on the death penalty with Krone at Albright College in Reading, Pennsylvania. His case is a tragic example of forensic science run amok.
In California, legislation, which took effect in January, makes it easier for a defendant to get a conviction overturned if an expert recants testimony. The law was enacted in response to an expert witness who recanted his bite-mark testimony in a high-profile homicide conviction.
Attorneys for 65-year-old William Richards, convicted in 1997 of killing his wife, have always maintained his innocence.
At Richards’ trial, expert Norman Sperber testified that only about 2 percent of people would have Richards’ unusual tooth feature. But later, with the help of a clearer photograph of the bite mark, he said Richards’ teeth were not consistent with the mark on his wife’s hand.
Sperber, now 86-years-old, recently told The Associated Press that he did not recall the details of Richards’ case, but he had always strived to be objective regardless of whether he was called by the defense or the prosecution.
“We’re not trying to convict somebody, we’re trying to get to the truth,” he said.
“More and more, experts are reconsidering their opinion not because they have pangs of guilt, but because in fact the science changes,” Laurie Levenson, a criminal law professor at Loyola Law School told The Associated Press. “You want a legal system that recognizes that reality.”