The New York City medical examiner's office is conducting an unusual review of more than 800 rape cases in which critical DNA evidence may have been mishandled or overlooked by a lab technician, resulting in incorrect reports being given to criminal investigators, the New York Times reports. Supervisors have found 26 cases in which the technician failed to detect biological evidence when some actually existed. In seven of those cases, full DNA profiles were developed — in some instances, evidence that sex-crime investigators did not see for years, hampering their ability to develop cases against rape suspects.
In one of those instances, the newly discovered DNA profile matched a convicted offender's sample, leading to an indictment a decade after the evidence was collected, said Dr. Mechthild Prinz, the director of forensic biology at the medical examiner's office. In two other instances, the new DNA profiles were linked to people either already convicted or under suspicion. The continuing review of the technician's cases underscores how DNA evidence, widely perceived as being nearly irrefutable proof of guilt or innocence, can still be subject to human error.