The former lab technician, Serrita Mitchell, said any problems must have been someone else’s.
“My work?” Ms. Mitchell said. “No, no, no, not my work.”
Earlier, the city medical examiner’s office, where Ms. Mitchell said she was employed from 2000 to 2011, said it was reviewing 843 rape cases handled by a lab technician who might have missed critical evidence.
So far, it has finished looking over about half the cases, and found 26 in which the technician had missed biological evidence and 19 in which evidence was commingled with evidence from other cases. In seven cases where evidence was missed, the medical examiner’s office was able to extract a DNA profile, raising the possibility that detectives could have caught some suspects sooner.
The office declined to identify the technician. Documents said she quit in November 2011 after the office moved to fire her, once supervisors had begun to discover deficiencies in her work. A city official who declined to be identified said Ms. Mitchell was the technician.
However, Ms. Mitchell, reached at her home in the Bronx on Friday, said she had never been told there were problems. “It couldn’t be me because your work gets checked,” she said. “You have supervisors.”
She also said that she had resigned because of a rotator cuff injury that impeded her movement. “I loved the job so much that I stayed a little longer,” she said, explaining that she had not expected to stay with the medical examiner’s office so long. “Then it was time to leave.”
Also on Friday, the Legal Aid Society, which provides criminal defense lawyers for most of the city’s poor defendants, said it was demanding that the city turn over information about the cases under review.
If needed, Legal Aid will sue the city to gain access to identifying information about the cases, its chief lawyer, Steven Banks, said, noting that New York was one of only 14 states that did not require routine disclosure of criminal evidence before trial.
Disclosure of the faulty examination of the evidence is prompting questions about outside review of the medical examiner’s office. The City Council on Friday announced plans for an emergency oversight committee, and its members spoke with outrage about the likelihood that missed semen stains and “false negatives” might have enabled rapists to go unpunished.
“The mishandling of rape cases is making double victims of women who have already suffered an indescribably horrific event,” said Christine C. Quinn, the Council speaker.
A few more details emerged Friday about a 2001 case involving the rape of a minor in Brooklyn, in which the technician missed biological evidence, the review found. The victim accused an 18-year-old acquaintance of forcing himself on her, and he was questioned by the police but not charged, according to a law enforcement official.
Unrelated to the rape, he pleaded guilty in 2005 to third-degree robbery and served two years in prison. The DNA sample he gave in the robbery case was matched with the one belatedly developed from evidence the technician had overlooked in the 2001 rape, law enforcement officials said. He was recently indicted in the 2001 rape.
Especially alarming to defense lawyers was the possibility that DNA samples were cross-contaminated and led to false convictions, or could do so in the future.
“Up to this point,” Mr. Banks said, “they have not made information available to us, as the primary defender in New York City, to determine whether there’s an injustice that’s been done in past cases, pending cases, or allowing us to be on the lookout in future cases.” He added, “If it could happen with one analyst, how does anyone know that it stops there?”
The medical examiner’s office has said that the risk of cross-contamination was extremely low and that it does not appear that anyone was wrongly convicted in the cases that have been reviewed so far. And officials in at least two of the city’s district attorneys’ offices — for Brooklyn and Manhattan — said they had not found any erroneous convictions.
But Mr. Banks said the authorities needed to do more, and that their statements thus far were the equivalent of “trust us.”
“Given what’s happened,” he said, “that’s cold comfort.”
