LONDON - A 25-year-old paranoid schizophrenic who beheaded an elderly woman during a 45-minute rampage through London back gardens was on Tuesday found not guilty of murder by reason of insanity and locked up indefinitely. Nicholas Salvador, a six-foot-tall cage fighter, believed that 82-year-old Palmira Silva was Nazi leader Adolf Hitler or a demon when he stabbed her repeatedly before cutting off her head and holding it aloft. The random attack took place last September in Edmonton, north London.