The gun used by illegal alien Juan Francisco Lopez Sanchez in what he claims was an accidental fatal shooting of a woman on San Francisco’s Pier 14 on July 1 has been determined to have been stolen from an unidentified Bureau of Land Management agent. Sources told the San Francisco Chronicle that the .40-caliber pistol was the agent’s personal firearm and had been stolen from his automobile not long before the shooting. Sanchez claimed that he found the gun wrapped in a T-shirt while sitting on a bench at the pier. “So I picked it up and ... it started...