They could have restrained him without resorting to choking him or cutting off his blood supply (I heard from one news agency that they did that). Since the coroner said he died of asphyxiation, then that trumps all what the various news agencies said. At my son's school, they used to have to restrain certain students (this was a class for autistic children and they were teenagers at the time). They would restrain the student but the student was never harmed. Some of these teens got pretty large, larger than the teachers.