Federal agents this week raided the office of the New Orleans Police Department homicide division, seizing the files and computer hard drives of two officers assigned to investigate police conduct in one deadly post-Katrina shooting episode, law enforcement sources told The Times-Picayune. Representatives of the FBI and NOPD confirmed the seizure late Thursday. FBI agents served a search warrant Wednesday afternoon for files in the offices of two supervisors, Sgt. Gerard Dugue and Sgt. Arthur Kaufman, the sources said. The two sergeants were the lead investigators who examined the shooting of civilians by police on the Danziger Bridge days after Hurricane Katrina. Gunfire from police, who were responding to reports of shots fired at officers, left two men dead and four people wounded.