Can you get in real trouble for doing this on AIM?

So a few days ago, my friend [age 12] was on AIM. He made a fake account and pretended to be this girl in our school Tiara. He was IMing a bunch of people saying some nasty stuff and one time he told me he regrets it, but he said to Tiara, "this is your mom" because her mom died. So Tiara and a couple of her friends guessed it was a girl in their cl who has no friends and who has a real attitude. So Tiara printed it and brought it to school. The VP got involved and told us the next dy to not cyber bully. He said that they were trying to get this person's IP address. My friend got really nervous. He doesn't want to tell that he did it because he knows he'll get into a lot of trouble and regrets what he did, and I don't blame him for being scared. I don't know how far they are taking this- if the cops are involved or not. I read online that people on AIM can only get your IP if you open a file they send you. Please tell me it's true I don't want to see him get in trouble. I am PRAYING that this will all fade away soon and everyone justs forgets about it and lives life on. So back to the problem, is there any way that they can find out it was him? And please don't suggest fessing up because I know him well enough to know that he never will. And this might be a bit of a devious idea, but is it possible for them to get the wrong address so that if they do trace it back to him, he can kinda lie about it. He also told everyone that he was talking to the fake Tiara too so that might back up the lies, don't you think? I know lies are wrong, but I know that for a fact, I would do the exact same thing if it were me. Oh and one more thing, because he's only 12, if they get the cops involved, can he go to jail or will they just give him a good warning and watch whatever he is doing and not let him go on the computer anymore?