OAKLAND, Calif. In an eight-day span, an Air Force sergeant fatally shot a federal security officer and wounded his partner outside a U.S. courthouse and ambushed and killed a California sheriff's deputy and injured four other officers, federal authorities said Tuesday. In announcing murder and attempted murder charges in the shooting of the security personnel, authorities alleged Staff Sgt. Federal authorities say the same homemade AR-15-style rifle was used in the two shootings. In their criminal complaint, federal officials described a hastily hatched plan to target federal law enforcement officials during the protest in Oakland. Justus is charged with aiding and abetting the murder and attempted murder of the federal officers.