You need to take the note to the police! if nothing else HEY will contact school and parents to get to the bottom of things.
My son in 7th grade had a similar experiance recently. I was sitting home and the phone rang. It was the principal wanting to know if my son was home from school yet. I said yes and asked why. he said it had been brought to his attention that my son had been talked about in a note passed around that the teacher found. It stated a date , time and place my son would be killed. it also listed a person as the executioner and how it would happen.!!!! The principal also said I was to bring my son to school myself until this was straightened out since it involved the school and a person from the school. My son DID know about the note and DID know who wrote it but asked me not to get involved because he would be embarassed. WRONG!!!!!! The principle contacted the other boys parents AND also made a police report because he felt it was THAT serious!!!! The boy was suspended and the police also talked to the other family stating it was not something to be taken lightly if their son thought such a thing was a joke!!!!!. Turns out it was a newer student who nobody knew that welll so who knows what the kid was trying to do!!!!!!!!
My only anger with the school was that the TEACHER had found the note and turned it into the office later, but then LET my son leave for the day .... the note stated he was going to be killed outside that day going to the bus
. What the hell was wrong with that teacher for leting him go to the bus by himself!!!! I don't blame the principal as the teacher did not turn the note into the office until the children had left that day. I just thank the principal for calling me immediately and checking to make sure my son was OK as soon as he found out!!!!!