The most amazing thing is that no one along the chain of escalation this must have passed (e.g. the teacher, the vice principal, the superintendent, the officer that arrived for the call, the sheriff, the prosecutor) - took a minute to stop and think:
"wait is this really the right way to go about handling this?"
Rarely is that done - everyone in the chain thinks "It's probably not serious, but I'd better pass it up to the next level just in case." No one is willing to take that responsibility for making the decision, so it gets escalated.
Some thing happened in the UK with the "Twitter Joke Trial":
"wait is this really the right way to go about handling this?"