More tainted DNA samples linked to sloppy work at NYC Chief Medical Examiner’s lab

The sloppy lab work recently uncovered at the Office of the Chief Medical Examiner is worse than first believed, with an internal review finding additional DNA samples were contaminated and that expired bleach was used to clean equipment, the Daily News has learned.
According to the ME’s Root Cause Analysis Report, of the 12,873 DNA samples tested from May 1 through Aug. 9., nine scientists — known as criminalists — were responsible for 26 DNA samples that were cross-contaminated, meaning the DNA being tested was tainted with someone else’s DNA. That number is more than three times higher than what the medical examiner initially reported two months ago.
As a result of the findings, 10 DNA profiles that had been uploaded to CODIS, or the Combined DNA Index System — a national system of DNA databases maintained by the FBI — had to be removed, according to the Nov. 9 report, a copy of which was obtained by the News.
None of those 10, the report noted, were linked to a known offender — meaning police had not arrested the wrong person or identified anyone as being linked to an unsolved crime.
The report made a series of recommendations, including calling for better supervision and training and improved cleaning protocols, and while it noted that expired bleach was used during the time frame examined, the committee “was unable to determine with certainty the root cause for the contaminations.”
Doing so would require taking a look back even further, the report said. But Julie Bolcer, a spokesperson for the ME’s office, said the problems were found because of the agency’s “robust quality assurance measures” and that the report “marks the conclusion of that process.
“[It] allows the agency to move forward and implement the suggested improvements,” she added.
But the Legal Aid Society said not looking back further at more DNA samples and how they were analyzed raises the possibility of innocent people having been charged.
“We are worried about how far back must the OCME go in order to determine the cause [of the cross-contamination],” said Jenny Cheung, of Legal Aid’s DNA Unit. “Is it months? Years?”
Cheung also noted that there are likely defense lawyers unaware that the DNA evidence in their clients’ cases was tested by the criminalists found to have done shoddy work — yet not identified in the report. Plus, she said, contamination in cases involving trace DNA evidence — small samples often found on weapons — is difficult to detect.
Citing a need for “urgency” to get to the bottom of the matter, she stressed, “DNA plays a significant role at trial and in plea negotiations. And, as much time passes, more people will need to make life and liberty decisions without the full understanding of the significant event.”
But Nathan Lents, a professor of biology at John Jay College of Criminal Justice, said it’s important to note the rate of cross-contamination was “very low.”
“So I don’t think there is cause for broad concern here,” Lents said. “What is happening here is this: As all of our techniques for DNA analysis get more and more sensitive, they require higher and higher standards to eliminate the possibility of cross-contamination. It is not surprising that observations on the ground lead to continual improvement of procedures.
“This is how it’s supposed to work,” he added, “and their transparency here is commendable.”
The cross-contaminations first came to light in September when the ME’s office, as required, explained them in a letter to the City Council and defense lawyers.
Per the letter, an analyst reviewing cases found that on June 11 a criminalist noted a match between four DNA profiles, suggesting the possibility of a repeat offender.
But it turned out that the criminalist had failed to properly clean the testing equipment, resulting in cross-contamination and a false DNA match. When the ME’s office looked further, it found two other criminalists were guilty of similarly slipshod work.
All told, at that time, there were eight DNA profiles found to have been cross-contaminated. Four of those had been entered into the federal CODIS DNA database and had to be hastily removed. That data is included in the recently conducted Root Cause Analysis Report, which uncovered the aforementioned additional instances of DNA cross-contamination, leading to six more DNA profiles being removed from the national CODIS database.