My .02 is that if he is not institutionalized, he might be allowed to attend a different school ?
It's hard to imagine this same school would accept him back !
Again my opinion is that he needs to be put away in an institution, possibly until he's an adult ?
But who knows ?
If he's let out early from juvenal detention, or a mental hospital that treats children -- and reoffends -- then he needs to be kept away from other children and the public at large, or he could commit murder the next time.
I worry that his mother will change schools, and then another adult or child could be harmed.
Imo.