Patrick Fitzgerald has scheduled a news conference Thursday to announce his resignation, according to the Justice Department. Fitzgerald was selected as northern Illinois' top prosecutor in 2001.
During his tenure he successfully tried two Illinois governors, George Ryan and Rod Blagojevich, and media mogul Conrad Black.
As a special prosecutor, he investigated Lewis "Scooter" Libby, then chief of staff to Vice President Dick Cheney. Fitzgerald's investigation led to Libby's conviction on charges that he leaked the covert identity of CIA agent Valerie Plame Wilson.