Forensic science

Stossel: Junk Science Locks Up Innocent People

DNA testing reveals that long-used forensic methods are error-riddled.


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TV shows like CSI, Law & Order, and NCIS depict incredible technology for identifying criminals.

In one NCIS scene, a 3D hologram identifies a person's teeth, precisely matching the killer's bite to a bite mark on a victim. "A little 3D magic for clarity and I give you—the killer's incisors!" NCIS character "Abby" announces proudly.

John Stossel loves crazy Abby, but notes that in the real world, court-approved experts reach similar conclusions—without good science to back them up.

Alfred Swinton was convicted of murder after "bite mark expert" Dr. Gus Karazulas said Swinton's teeth matched a bite on a victim.

Karazulas told the TV show Cold Case Files: "We look at the evidence and we make sure that if we are going to make a decision it's gonna be a truthful decision."

But a decade later, DNA testing showed it was not Swinton's DNA on the bite mark. He was released after 18 years in prison.

To his credit, Karazulas now admits he was wrong. "Bite mark evidence is junk science," he tells us by email. He testified to that in court and resigned as a member of the American Academy of Forensic Sciences.

The verdict was wrong because bite mark analysis has never been scientifically proven, says Chris Fabricant of the Innocence Project, which represented Swinton.

Fabricant tells Stossel that bite mark analysis "is similar to you and I looking at a cloud, and then I say, 'John, doesn't that cloud look like a rabbit to you?' And you look at it and say, 'yeah, Chris, I think that does look like a rabbit.'"

Many experts agree. "Bite mark analysis is a subjective method," reads a 2016 report by the President's Council of Advisors on Science and Technology, which notes that even the most positive studies on it find an error rate of 1-in-6.

NYPD detective Harry Houck tells Stossel that he agrees bite mark analysis has problems, but that it can be used as one piece in a puzzle to convict people.

Other methods have flaws, too. Even fingerprint analysis sometimes goes wrong, as do carpet fiber evidence, gun tracing, and hair matching.

Stossel asks Fabricant: "Why do judges admit this stuff? Why don't defense attorneys get it thrown out?" Fabricant answers: "We all went to law school because we don't know science, we don't know math. And if somebody comes in in a white lab coat…that's good enough for government work."

That shouldn't be the standard, says Stossel. Jurors and judges should be much more skeptical of "scientific" evidence.

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The views expressed in this video are solely those of John Stossel, his independent production company, Stossel Productions, and the people he interviews. The claims and opinions set forth in the video and accompanying text are not necessarily those of Reason.