Lots of people reported the most recent big troll thread, but it obviously trundled on for a while regardless - I presume while you were looking into it behind the scenes. How about a system whereby if you've received a certain amount of reports, the thread is automatically "paused"/locked/hidden while you investigate?
And if a thread is revealed to have been from a troll, delete it (with the message "Yawn" or similar), and keep it up for a day or two but hide it from everyone apart from those who were posting on it (op excluded, obviously), so that they can discuss it among themselves without their discussions being public. I'm sure the trolls get a kick out of being called a sick fucker as much as from the original deception; as it's an attention-seeking phenomenon, the less attention they get, the better, no?