By STEFANIE DAZIO, Associated Press LOS ANGELES (AP) — The 16-year-old boy who fatally shot two fellow students and wounded three others last week at a Southern California high school used an unregistered, untraceable “ghost gun,” Los Angeles County Sheriff Alex Villanueva said Thursday. Villanueva told media outlets that Nathaniel Berhow’s .45 caliber, 1911-model replica semi-automatic pistol was