Lawyers for Boston mobster James "Whitey" Bulger have asked a federal appeals court to order the judge scheduled to preside over his trial to step aside because of his close ties to the U.S. Justice Department.

The Boston Globe reports that in a motion filed Tuesday, Bulger's lawyer said that if the 1st U.S. Circuit Court of Appeals fails to grant his request, Bulger's trial "will go forward under a dark cloud."

Bulger's lawyer argues that Judge Richard Stearns' ability to be impartial is questionable because he was a top prosecutor in the U.S. attorney's office in the 1980s and is a close friend of FBI director Robert Mueller.

The 83-year-old Bulger is scheduled to go on trial in June for his alleged role in 19 slayings.