From the sounds of it, he's too dangerous for anyone to be going after. And doesn't seem to care who he kills or doesn't kill.

[ there's a lot he wants to know about this 'Lucifer' too, but it can wait. ]

There's more to a task force than physically going after a suspect. Can't you give him something, away from the action? It'll keep him out of harm's way, and you'll be giving him something to do with his time.