John Walker / Getty ImagesFormer Hells Angels boss, Merl Hefferman, allegedly disposed of four group members’ bodies by cremating them at a Fresno funeral home that the gang called “the pizza oven.” Federal prosecutors laid the case out during Hefferman’s sentencing, who had pleaded guilty in December for disposing of Joel Silva’s body. Levi Phipps, the crematory manager, said during the trial that he was threatened at gunpoint by two men while they put a body into the incinerator. Hefferman the