More than six years after the FBI crime laboratory was rocked by controversy, the Justice Department has identified about 3,000 criminal cases that could have been affected by flawed science and skewed testimony. Government officials told The Associated Press they are aware of between 100 and 150 cases in which prosecutors have alerted defendants of problems they concluded were material to verdicts. None has resulted in overturned convictions, they said. The identification of cases and prosecutorial reviews are the final stages of a scandal that shook the FBI during the mid-1990s when a senior chemist at the famed crime lab went public with allegations of shoddy work, tainted evidence and skewed testimony. A Justice Department internal investigation concluded in 1997 that 13 lab technicians made scientific errors in cases or slanted testimony to help prosecutors. Several were reprimanded, but none was fired or prosecuted. Some criminal defense lawyers are concerned by the Justice Department's decision to let federal, state and local prosecutors decide whether to notify defendants of problems. That's like asking the fox to guard the hen house," said former federal prosecutor Neal Sonnett. He is past president of the National Association of Criminal Defense Lawyers. "If there is a possibility that evidence has been tainted, then the Department of Justice or prosecutors should not be the arbiter of whether it's material," Sonnett said.