Scientists question the validity of bite mark evidence

Scientists question the validity of bite mark evidence

On Behalf of | Aug 16, 2021 | Criminal defense

Texas residents who watched the Netflix series “The Innocence Files” will likely be familiar with the case of a Mississippi man who was convicted of murder and sentenced to death for killing a 3-year-old girl in May 1992. Prosecutors in the case had no motive, eyewitnesses or DNA evidence, but they did have a forensic odontologist who testified that he was certain the defendant had left 19 bite marks on the victim’s body. An expert defense witness pointed out that bite mark evidence is subjective and unsupported by scientific evidence, but the jury still voted to convict.

Wrongful convictions

The man’s conviction was overturned in 2001 when a more rigorous DNA test performed on samples gathered from the victim proved beyond any doubt that somebody else had committed the crime. Recent studies suggest that this type of miscarriage of justice is all too common in the United States. The Innocence Project says that it is aware of at least 26 cases involving innocent defendants who were convicted because of unscientific bite mark evidence, and the National Registry of Exonerations has concluded that false or misleading forensic testimony plays a role in one in four wrongful convictions.

Bite mark evidence

Groups calling for prosecutorial reform and criminal defense attorneys asked questions about the reliability of bite-mark comparisons in 2009 when the National Academy of Sciences released a report criticizing the technique and several other unproven forensic methods. The American Board of Forensic Odontology responded to the NAS report by asking experienced odontologists to analyze photographs of marks left on human skin. The researchers were shocked to discover that many of these experts could not even identify a bite mark let alone match one to a particular individual.

Texas exoneration

Prosecutors in Texas are unlikely to rely too heavily on bite mark evidence because the state’s Forensic Science Commission has stated publicly that it does not meet the commonly accepted standards of forensic science. The agency reached this conclusion following an investigation lasting six months that was launched in 2016 after the Texas Court of Criminal Appeals overturned the wrongful conviction of a man who was sent to jail because of misleading bite mark evidence.