this is going to be a controversial take but i’m sorry, a behavior plan is put in place for this reason. you do not take away an autistic persons possessions without warning or reading how to do so. If you’re working with Autistic children you HAVE to follow the IEP so this doesn’t happen. if this child was this violent then he simply shouldn’t have been in a public school setting so that’s a failure on the system. many steps were missed before this child acted violently