The Arizona sheriff helping investigate the shooting of Rep. Gabrielle Giffords and others says the gunman may not have acted alone.
Pima County Sheriff Clarence Dupnik said at a news conference in Tucson on Saturday that authorities may have a photo of another suspect.
Dupnik says officials believe a suspect in custody may have come to the grocery store parking lot with another person, and that person was in some way involved.
Dupnik would offer no other information.
People familiar with the investigation have identified the suspected gunman being held as 22-year-old Jared Loughner.