Speaking of cop and medic: there's also a significant chance that mafia has the core of death. Medic only prevents deaths during the night, while core of death kills the day after. It's one use only and Raiden can still deflect the effect elsewhere. Still, cop seems like the most obvious target for it.
I agree with rob on doc targets, merely wanted to point out that there are no huge reasons not to use it on whomever you feel like.