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  1. #49


    F.B.I. Audit of Database That Indexes DNA Finds Errors in Profiles

    The Federal Bureau of Investigation, in a review of a national DNA database, has identified nearly 170 profiles that probably contain errors, some the result of handwriting mistakes or interpretation errors by lab technicians, while New York State authorities have turned up mistakes in DNA profiles in New York’s database.
    The discoveries, submitted by the New York City medical examiner’s office to a state oversight panel, show that the capacity for human error is ever-present, even when it comes to the analysis of DNA evidence, which can take on an aura of infallibility in court, defense lawyers and scientists said.
    The errors identified so far implicate only a tiny fraction of the total DNA profiles in the national database, which holds nearly 13 million profiles, more than 12 million from convicts and suspects, and an additional 527,000 from crime scenes. Still, the disclosure of scores of mistaken DNA profiles at once appears to be unprecedented, scientists said.


    The errors had the effect of obscuring clues, blinding investigators to connections among crime scenes and known offenders. It remains to be seen whether the new DNA evidence will cast doubt on any 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 mistakes were discovered in July, when the F.B.I., using improved software, broadened the search parameters used to detect matches. The change, one F.B.I. scientist said, was like upgrading or refining “a spell-check.” In 166 instances, the new search found DNA profiles in the database that were almost identical but conflicted at a single point.
    Alice R. Isenberg, the chief of the biometric analysis section of the F.B.I. Laboratory, said that most of the 166 cases probably resulted from interpretation errors by DNA analysts or typographical errors introduced when a lab worker uploaded the series of numbers denoting a person’s DNA profile.
    “We were pleasantly surprised it was only 166,” Dr. Isenberg said, referring to the number of cases. “We were quite worried it would be much higher than that,” she said. “These are incredibly small numbers for the size of the database.”


    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, which appears graphically as a series of peaks, somewhat like the record a seismograph produces.
    “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.
    In court, prosecutors often describe the strength of DNA evidence against a defendant with numbers that can run into the billions — expressing how unlikely it is that a person chosen at random would also have a DNA profile linked to the crime scene. But the rate of errors by a lab or a technician, a less dramatic topic, can be a much more relevant statistic, many defense lawyers and some scientists said.
    “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.


    One of the errors involved the analysis of DNA found on a gun that had been handled by several people and used in a shooting in the Bronx in 2010. A man, Marc Outram, was indicted on the basis of eyewitness testimony from a police officer, even though Mr. Outram’s DNA profile was deemed as conflicting with the DNA mixture found on the gun, the authorities said. Following the discovery of an analyst’s error, the authorities again examined the DNA from the gun, this time discerning a different DNA profile. The results again excluded Mr. Outram, and the new DNA profile appeared to match another person in the database.
    Bronx prosecutors plan to drop the case against Mr. Outram, 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.”

  2. #50


    Courtesy of ws poster observation and our friend Punisher, big news on the DNA front.

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