Bite mark analysis has no basis in science, experts now say. Why is it still being used in court?

Even now, as a free man, Keith Harward finds it hard to explain what it was like to sit in a courtroom, on trial for a rape and murder he knew he didn’t commit, watching someone considered an expert testify with certitude that bite marks on the victim’s leg matched his teeth.

“I still to this day wonder what the hell just went on,” he told NBC News at his home in North Carolina. “Sometimes I break down and bawl, because I can’t explain to you or anybody else, other than people who’ve been in my situation.”

No evidence connected Harward to the horrific 1982 crime, but he happened to be among a group of sailors from a Navy ship in dry dock in Newport News, Virginia, who were required to give dental impressions, since the assailant had been wearing a Navy uniform. Two forensic dentists told two separate juries that Harward’s teeth matched “to a scientific certainty” a bite mark on the rape victim’s skin. Harward spent 33 years in prison until, with the help of the Innocence Project, he was exonerated in 2016 by DNA evidence that pointed to another sailor as the killer.

Keith Harward talks to reporters as he is released from Nottoway Correctional Facility in Burkeville, Va., on April 8, 2016. (Daniel Sangjib Min / Richmond Times-Dispatch via AP file)
Keith Harward talks to reporters as he is released from Nottoway Correctional Facility in Burkeville, Va., on April 8, 2016. (Daniel Sangjib Min / Richmond Times-Dispatch via AP file)

The Innocence Project says Harward is among at least 36 people who have been exonerated after having been wrongfully convicted based on now-debunked bite mark comparisons. One of them, Eddie Lee Howard, was on death row in Mississippi when he was freed in 2021 after crime scene DNA was matched to someone else.

Four separate governmental scientific bodies have concluded that bite mark analysis has no basis in science. That includes the President’s Council of Advisors on Science and Technology, which said in 2016 that “available scientific evidence strongly suggests that examiners not only cannot identify the source of bitemark with reasonable accuracy, they cannot even consistently agree on whether an injury is a human bitemark.” The National Institute of Standards and Technology, the gold standard of measurement science, said in 2022 that bite mark forensics “lacks a sufficient scientific foundation” because “human dental patterns have not been shown to be unique at the individual level.”

One 2016 study found that self-described experts couldn’t distinguish between human and animal bite marks. Others have documented how marks in human skin change over time through healing or decomposition.

“People that were board certified did not agree about what a bite mark was,” said Adam Freeman, a forensic dentist who once “drank the Kool-Aid” of bite mark analysis but has since become one of its biggest critics within the profession. “If a science is not a science, and it’s not reproducible, and it’s not reliable, courts of law should not allow it in, period.”

Photo of a mold of Keith Harward's teet used in his trial. (Court exhibit)
Photo of a mold of Keith Harward's teet used in his trial. (Court exhibit)

Yet bite mark analysis has been used in thousands of cases. And while it has increasingly been successfully challenged by defense lawyers, no court has ruled it inadmissible.

“There are still many people — and we don’t even know how many — still in jails because of bite mark testimony,” Freeman said. “It really is horrifying that this still is allowed to be used in courts of law, where these are issues of life and liberty.”

Chris Fabricant, an Innocence Project lawyer and author of “Junk Science and the American Criminal Justice System,” said his team has consistently blocked the introduction of bite mark evidence in courts around the country, even as it continues to seek the exoneration of defendants imprisoned based on the discredited discipline. But he said none of the forensic dentists who testified based on what are now discredited methods have been held accountable.

“My sense of outrage is what gets me out of bed every day,” he said.

Freeman said, “I can tell you that literally thousands of human years have been spent in jail” based on faulty testimony.

Bite mark photos used in the trial of Mark Harward. (Court exhibit)
Bite mark photos used in the trial of Mark Harward. (Court exhibit)

There is no data showing how often bite marks have been used in prosecutions. Anecdotal evidence suggests that the number has declined steeply, but that prosecutors still sometimes try to introduce bite marks at trial.

Professional associations of forensic odontologists responded to the NIST report by saying that while they agree with “many details” in the report and “know the issues surrounding bitemarks and acknowledge past concerns,” the NIST’s rejection of bite mark evidence is too broad.

“Critics continue to overlook the strides made … by forensic odontology to address these concerns. It is crucial to reiterate that the cases where odontologists misidentified bite perpetrators occurred in the 1980s and 1990s. Today’s odontologists do not adhere to the standards that were in place during that era, yet we continue to be judged by them.”

‘It is a nasty place’

Charles McCrory is spending his 38th year behind bars, convicted of killing his wife. The bite mark expert in his case recanted his testimony, saying he now knows he cannot say whether a bite mark on the victim matched McCrory’s teeth. Yet the Alabama courts have declined to free McCrory.

Charles McCrory. (Alabama Department of Corrections)
Charles McCrory. (Alabama Department of Corrections)

Alabama’s Court of Criminal Appeals ruled earlier this year that the jury was capable of deciding on its own whether the bite marks matched, a finding that ignores science suggesting such perceived visual matches cannot be valid. The court also cited other evidence in the case, including a witness who said he saw McCrory’s truck at the house during the time of the murder. No physical or forensic evidence links him to the crime.

Three years ago, after the bite mark evidence in his case collapsed, McCrory was offered a deal: Plead guilty and walk free. He refused.

“I refused to take it because I didn’t kill her,” McCrory told NBC News from his prison facility. “I did not kill my wife.”

A bite mark photo presented as evidence in the trial of Charles McCrory. (Court exhibit)
A bite mark photo presented as evidence in the trial of Charles McCrory. (Court exhibit)

The Innocence Project is now pursuing appeals through the federal courts.

“Prison is hard — a lot of the stories that you see on the news about prisons, particularly Alabama prisons, are true,” McCrory said. “It is a nasty place, and it’s not a place I would wish on anyone.”

“I don’t give up hope,” he said. “And certainly there’s days of disappointment and days when you’re down and out … but I just believe that somewhere there’s a truth in this that will come out, and you can’t give up. That’s just not an option.”

Harward, released in 2016, is living proof that a second act is possible after decades spent wrongfully locked up. Awarded $1 million in compensation by Virginia, the 67-year-old lives quietly in rural North Carolina, taking occasional RV trips with his girlfriend and puzzling over smartphones and social media.

But he also continues to speak out about bite mark evidence, which robbed him of half his life and kept him from attending his parents’ funerals.

“It’s garbage. It’s crap. It doesn’t mean anything,” he said.

A few years ago, he traveled to a conference of forensic dentists in New Orleans to confront them about bite marks. Many were sympathetic, he said, but there is an old guard that clings to the past.

“How many times do you have to be told you’re wrong before you give it up?” he said.

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