“Richards had already been incarcerated for 15 years when, during an evidentiary hearing in 2008, the state’s star witness, Dr. Norman “Skip” Sperber, a legend within the odontology community, recanted his previous testimony, saying that he had been wrong about the mark on Pamela’s hand. He said he had based his findings on bad photographic evidence, and drawn conclusions that he could no longer support.
Sperber was not alone in rethinking the kinds of conclusions one could draw based on such visual analysis. In 2009, the National Academy of Sciences released a groundbreaking report on the state of forensics, which seriously questioned a range of forensic disciplines used in criminal cases as flawed and unscientific. In particular, the authors wrote, pattern-matching branches like bite mark evidence lack any actual scientific underpinning. Indeed, pattern-matching forensics rely entirely on so-called “experts” analyzing visual evidence based on subjective criteria.”