FBI director Robert Mueller answers questions during a press conference at Pima County Sheriff's Dept. headquarters on Sunday. Benjie Sanders/Arizona Daily Star

Jared Lee Loughner, the suspect in Saturday's mass shooting at a Tucson Safeway store, is formally facing five federal charges.

According to a complaint filed today by the U.S. District Attorney's Office, Loughner is charged with killing U.S. District Court Chief Judge John Roll and Gabriel Zimmerman, a staff member of U.S. Rep. Gabrielle Giffords.

He's also charged with attempting to murder Giffords and two other members of her staff, Pamela Simon and Ron Barber.

Loughner is scheduled to make his initial court appearance at 3 p.m. Monday before Magistrate Judge Lawrence Anderson at the Sandra Day O'Connor Courthouse in Phoenix. He remains in federal custody.

Contact reporter Kim Smith at 573-4241 or kimsmith@azstarnet.com