Agreed, what they did was juvenile and cruel, as well as illegal. Did it contribute to the kid’s decision to kill himself, clearly. But I don’t think they are legally culpable in criminal court. The family may go the wrongful death route in civil court though.
That's your opinion, not a fact. FWIW it's my opinion too, but in a court of law, it won't mean bupkis.
They may sue the school, too. Apparently, there were messages posted on a gay forum by someone who’s situation was identical to Tyler’s. The poster “cit2mo”, claimed to have informed his RA about the roommates behavior when he was filmed the first time.
http://www.nj.com/news/index.ssf/2010/09/message_board_thread_on_gay_we.html