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.

In some cases, the discovery of an error has enabled the authorities to identify new suspects in cold cases. One such discovery has breathed new life into the murder investigation of a man found bludgeoned to death in the Bronx in 1998. It also led to new matches in two rape cases in New York City in the 1990s, although the statute of limitations for prosecution appears to have expired. In these examples, the errors were found in the DNA profiles taken from the crime scenes rather than from people convicted of crimes.

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.

FUENTE: New York Times
http://www.nytimes.com/2014/01/25/nyregion/fbi-audit-of-database-that-indexes-dna-finds-errors-in-profiles.html?action=click&module=Search&region=searchResults%230&version=&url=http%3A%2F%2Fquery.nytimes.com%2Fsearch%2Fsitesearch%2F%3Faction%3Dclick%26region%3DMasthead%26pgtype%3DHomepage%26module%3DSearchSubmit%26contentCollection%3DHomepage%26t%3Dqry926%23%2Fdatabase&_r=0