The Federal Bureau of Investigation recently reviewed some of the national DNA database and identified 170 profiles that contained errors.  Some of the errors were the result of handwriting mistakes or lab interpretation errors.  New York State authorities also found mistakes in their DNA database.  The discoveries, submitted by the NYC Medical Examiner’s Office to a New York Oversight Panel, show that the capacity for human error in the justice system is always present, even when it involves DNA evidence, which has a sense of infallibility in the courtroom.

The errors identified so far implicate a tiny fraction of the total DNA profiles in the national database.  The database holds at least 13 million profiles, including suspects, convicts, and crime scene evidence.  The disclosure of mistaken DNA profiles appears to be unprecedented, scientists say.  The discovery of an error has enabled authorities to identify new suspects in cold cases.  One discovery renewed a 1998 murder case in the Bronx and another led to matches in two rapes in NYC in the 1990s.  The errors in those examples were from the crime scene rather than a wrongful conviction.

Errors can obscure evidence and blind investigators.  It remains to be seen whether the DNA mistakes will cast any doubt on already closed cases.  Dan Krane, a biology professor at Wright State University, said the disclosure was the government’s clearest acknowledgment to date that “there are mistakes in that database.”

The FBI was improving software in the database to be able to broaden search parameters when the mistakes were discovered.  The change was likened to refining “spell-check,” according to one F.B.I. scientist.  The audit found that most of the DNA mistakes in the database were off by one single point.

Alice R. Isenberg, the chief of the biometric analysis section of the F.B.I. Laboratory, said that most of the cases most likely resulted from interpretation errors by analysts or typographical errors when a lab worker uploaded the series of numbers representing a person’s DNA profile.  It is still possible that some of the cases involved DNA from different people that are remarkably similar genetically.  In a number of the cases, the slight differences have already been tracked back to errors.  According to documents, what appeared to be DNA profiles of two people were in fact, the profile of one person.

A review by the New York City medical examiner’s office determined that six of the cases were attributable to errors in DNA profiles it generated from crime scenes in New York, according to a letter the office sent to the state panel.

Since the discovery of the errors at the national level, the New York State Police have changed their search parameters, finding additional errors.  State databases include profiles that do not meet requirements for inclusion in the federal database for reasons ranging from degradation of the sample to complex mixtures of multiple people.

In two of the errors discovered in the state database, analysts at the city’s medical examiner’s office made mistakes as they tried to discern a DNA profile from raw data.

“These revelations spotlight how human error can detract from the reliability of the testing process,” said Alan Gardner, the head of Legal Aid’s DNA Unit, which is challenging the city medical examiner’s methods for discerning DNA profiles in complex mixture cases.

At trial, prosecutors often highlight the strength of DNA evidence, expressing the unlikeliness that a person chosen at random would have the DNA profile linked to the crime scene.  Error rate, at times a much more relevant statistic, isn’t a popular topic.

“If we say there is a 1-in-10-quadrillion chance that someone else might have the same DNA profile, but there is also a 1-in-10,000 chance that there was a mistake in generating the profile, the only number the jurors should be paying attention to is the error rating,” said Dr. Krane, who was once on a forensic science commission for the State of Virginia and now consults with defense lawyers on DNA cases.

Other than New York, it is unclear whether other states are undertaking an audit of their DNA databases.  At the national level, there has not been a full accounting of mistaken cases, which defense attorneys and former lab scientists find a troubling fact.  While the F.B.I. administers the software linking the state and federal DNA databases, it knows little about the actual profiles.

“We don’t have oversight,” said Dr. Isenberg, of the F.B.I. Laboratory. “It’s up to the labs…”

Barry Scheck, a co-founder of the Innocence Project and a member of New York’s new Forensic Science Commission, said in an interview, “It’s hard for [the FBI] to dictate what follow-up the state and local authorities will undertake.”

Bruce Budowle, a former F.B.I. scientist now at the University of North Texas’s Health Science Center, said, “For the FBI to say, ‘It’s the states’ problem’ and that’s the end of it, that’s the ostrich burying its head in the sand and not contributing to improvement of the process.”

Scheck added that the errors underscored the need for information-sharing among entities in the criminal justice system to ensure that evidence receives consideration even if someone has already been convicted.  One of the errors involved the analysis of DNA found on a gun that had been handled by several people and was used in a Bronx shooting in 2010.

Marc Outram was indicted on the basis of eyewitness testimony from a police officer, even though his DNA profile conflicted with the mixture found on the gun.  Following the error, the authorities re-examined the mixture and discerned a different DNA profile.  The results again excluded Outram and the new profile matched another person in the database.  Bronx prosecutors plan to drop the charges, said Steven Reed, a spokesman for the Bronx district attorney’s office, adding that the case was “going to be dismissed for reasons other than the problem with the DNA profile.”

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