Bitemark Analysis: Is It Junk Science?

Bitemark evidence is often used in trials to convict defendants but is it reliable?

After 18 years behind bars, Alfred Swinton of Connecticut was released from prison with the help of The Innocence Project.

The evidence that got him convicted is the same evidence that got him exonerated: bitemark analysis, which is when a forensic dentist takes measurements of what appear to be bitemarks and then they compare it to the mold of a suspect’s teeth.

New evidence has proven that a bite mark on the victim originally attributed to Swifton didn’t belong to him after all, In fact, the dentist who originally testified against him for the 1991 murder of Carla Terry recently recanted his testimony. DNA testing also excluded him as the source of male DNA found under Terry’s fingernails. On March 1, 2018, a judge exonerated Swinton.

“Bite mark evidence represents everything that is wrong with forensic science in this country today,” Chris Fabricant, Director of Strategic Litigation for the Innocence Project told Oxygen.com. “It’s grossly unreliable even under ideal circumstances and it has contributed to more wrongful convictions and indictments than any other technique that is still admissible by criminal trials today.”

He added that bite mark practitioners do not undergo any proficiency testing and actually have no idea how often they are right and how often they are wrong when it comes to bite mark analysis.

“Nonetheless, the evidence is very, very powerful compelling evidence,” Fabricant said. “Not only does it place the suspect’s teeth on the victim itself where it also allows the prosecution to depict the suspect as an animal to a jury. [...] The trouble is that forensic dentists cannot even identify what is and what is not a bite mark. The idea that the courts continue to admit this type of evidence is really an outrage and a disgrace for our criminal justice system that still allows this type of evidence.” 

When it came to Swinton, Fabricant said there was no question that the marks on Terry’s body were bitemarks. Still, Fabricant said the forensic dentist got it wrong, anyway.

“What it demonstrates is that even under ideal circumstances, this evidence is grossly unreliable and should never be admitted to convict anybody,” Fabricant told Oxygen, adding that Swinton’s conviction and incarceration destroyed Swinton’s family. “He had never been convicted of a crime and suddenly he was thrown in prison and accused not only of this crime but of a series of similar murders. He was accused of being a serial killer.”

Michael J. Saks, a professor of law at the Sandra Day O'Connor College of Law at Arizona State University, told Oxygen.com that “forensic dentists have failed to carry out the research to prove the validity of what they do.”

Saks provided Oxygen with an article he wrote with the assistance of other experts, entitled "Forensic bitemark identification: weak foundations, exaggerated claims" for the Journal of Law and the Biosciences.

The article’s main takeaway?

“The rise and impending fall of bitemark evidence powerfully illustrates the costs of the failure to assure that what enters our criminal courts is sound science.” 

Swinton was featured on an episode of "Forensic Files" which claimed that bitemark evidence solved the case.

Ironically, the forensic dentist states in the clip that, "In my field, if I make a mistake a man goes away for the rest of his life.  So there are no tests, no difficulties that we cannot bear to make sure we don't convict an innocent person."

Fabricant told Oxygen that The Innocence Project searches for cases where a conviction was based off bite mark evidence because those cases are so flimsy. Often the people convicted are actually innocent. 

“I ask my paralegals to get me any case that involves bitemark evidence because any case that rests on bitemark evidence is unreliable,” Fabricant said. “Every single one of those cases that we have litigated, unless it is still currently pending — the defendant has been exonerated.”

The Innocence Project has helped get thirty wrongful convictions and indictments which relied heavily on bitemark analysis overturned.

If it’s so unreliable then why is it still used?

“Once an indictment has been secured, and the case is going to trial, the gloves come off and the adversarial process kicks in and the combatants [in this case, the prosecution] use all the weapons at their disposal,” Fabricant said. “It’s admissible evidence and prosecutors are going to use whatever they can use to admit the evidence, save a few data-oriented prosecutors who have recognized that the truth-seeking function of the justice system is undermined by the use of unreliable evidence. Justice is not advanced through the introduction of junk science.”

A 2009 report from the National Academy of Sciences National Research Council backs up Fabricant’ stance. That report found that bite mark analysis lacks scientific validity.

A second study, undertaken by the President's Counsel of Advisory on Science and Technology [PCAST], came to even stronger conclusions in 2016, finding "bitemark analysis does not meet the scientific standards for foundational validity, and is far from meeting such standards.”

As for Swinton, he’s happy to be out of jail after his wrongful conviction.

“Our exonerees — and Alfred is no different — have displayed time and time again incredible grace and this is because in my view the kind of character that it takes to persevere through decades of wrongful conviction. These are unique human beings,” Fabricant said. “I have never heard Mr. Swinton express the kind of outrage that I think anyone would expect that they themselves would feel if they experienced such an injustice.”

The only big concern that Swinton has expressed, according to Fabricant, is worry that the real killer is still at large.

[Photo: Department of Corrections]