Why is a 7th grade boy still in my daughter's school after asking her to join a suicide pact with him?

Not only did he beg her to commit suicide with him (in 4 different letters that were confied), he also brought 4 knives to school and told the principal that they belonged to my daughter. I thought congress ped a Zero Tolerance law. This boy was supposed to be expelled but after a few weeks returned. Shouldn't I have been informed of his return?