Yeah Hofsteader only died recently and Maria hadn't died, so I suspect Terry's premature death left him with some time to uh kill until he can fully dopplegang the strip bar guy. I still don't know why The Boogeyman is preoccupied with getting popped by the cops, OR why his argument is so bad for "stopping". He's like heh heh let me kill children because if you don't something REALLY bad will happen, like I'll kill...ADULTS. Apparently supernatural monsters don't know how to manipulate people.
This episode for sure didn't give us much new information, though I think it's still very watchable and moving.
I've seen more than enough evidence of this not being the case, there is a real lack of cooperation between law enforcement agencies and a lot of jurisdictional cock walking. Plus everybody agreed Terry did it and then he died so essentially there isn't much of a case they have to follow up on, and the stuff they found in the barn post mortem only added to the evidence against Terry.
The investigation now has nothing to do with GBI, that guy is just being probably really unprofessional by sharing info with Ralph, because he himself is confused by the evidence.