As hyke said, if SG still has the logs of his MSN shite, then they can be used. Send them to your local police, with copies to the FBI and Scotland Yard. You won't have to face him, but if they want to act, they will take it from there. What he is doing is illegal because paedophilia and child porn are illegal acts made that way by authorities all over the world.
Maybe nothing will be done either, but it's worth a try.