When cops stopped Antonio Sing-Ledezma's car following a shooting outside El Paso, Texas, in March and asked him if he had anything illegal on him, he didn't mention the handgun with the scratched-off serial number hidden in the vehicle. Sing-Ledezma, who did admit to having some marijuana and a glass pipe in his jacket pocket, told the officers that he had just been shot. When they asked him who pulled the trigger, however, he became uncooperative. A subsequent search of his vehicle turned up the weapon. A Mexican citizen wanted for murder in his home country who'd previously been deported...