A single lab technician's mistakes mean a full review of over 800 rape cases in New York City, as medical examiners search for any errors in the DNA evidence.
A lengthy review of a technician's work after she repeatedly made mistakes in a training class she was taking led administrators to uncover a host of other possible errors committed from 2001 to 2011.
"The review found that the technician sometimes overlooked stains, while at other times she identified stains but then made errors in the chemical test used to detect semen and reported not finding anything," said the Wall Street Journal.
"In seven of the cases, full DNA profiles were developed, and in one the new profile matched a convicted offender's sample, leading to an indictment a decade after the evidence was collected. In two other instances, the new DNA evidence was linked to people already convicted or under suspicion."
Some of the evidence was misplaced or simply overlooked, and in one instance was mixed with evidence from other cases, resulting in possible cross contamination.
"Our guess is the technician had both kits open at the same time, and when she was reassembling the case files, evidently she had misplaced the evidence items from one kit to another," Eugene Lien, a quality assurance manager with the medical examiner's office.
None of the mistakes led to false accusations or convictions, say officials.
In each rape case, DNA evidence must be carefully handled amd thoroughly tested..
"The technician had two responsibilities when processing rape kits: She had to snip cuttings from swabs taken from victims' bodies and place them in test tubes for DNA analysis by more experienced lab workers," said the New York Times.
"She also inspected the victims' clothing, usually underwear, for stains that might indicate DNA. Sometimes she overlooked stains, the review found. At other times, she identified stains, but then botched the chemical test used to detect semen and reported finding nothing."