FBI reduces DNA backlog, scales back roadside bomb tests WASHINGTON (Reuters) - The FBI has sharply reduced a backlog of forensic DNA testing, in part by scaling back fruitless tests of hair samples from roadside bombs in Iraq and Afghanistan meant to identify who placed them, according to a report released on Tuesday. The report by the Justice Department's inspector general measured how quickly the FBI lab processed DNA evidence in cases such as bombings, killings and missing persons. The FBI has faced criticism that its testing is too slow and could delay the capture of criminal suspects and the possible exoneration of innocent people. Testing has improved, the report said. The FBI lab's DNA backlog - defined as the number of active cases - dropped to 400 this year from 3,200 in 2010. The report said one reason was a 2011 decision to stop automatically testing hair samples from roadside bombs abroad. Testing all samples drew DNA examiners away from domestic law enforcement cases, the report said, adding "there have been no documented instances" in which hair testing succeeded in identifying the source of a roadside bomb. The FBI retains hair samples for possible testing later, if warranted. It also continues to test other kinds of evidence from roadside bombings, although its two DNA lab units limit requests to no more than 700 per year. Other factors, such as additional training and the automation of lab work had an even greater role in reducing the FBI lab's backlog, the report said. In what the report called "a significant achievement," one of the FBI laboratory's two DNA units has no backlog. That unit tests fluid stains, like blood and semen. DNA evidence reviews are crucial to resolving many legal proceedings and in processing a crime scene. While some U.S. jurisdictions have their own DNA labs, the FBI's lab based in Quantico, Virginia, handles testing for those that do not and for federal cases. The FBI was pleased with the report and remains committed to promptly evaluating DNA evidence, D. Christian Hassell, assistant director of the FBI's laboratory division, wrote in a letter to the inspector general. Editing by Howard Goller and Stacey Joyce