Mostly sure it is the guy that killed the other guy in the community event. Or something like that...! Not "playing" this event so I don't have all details but I guess it is somewhat related.
The serial killer? 😜
Yes. It is probably someone that turns into a werewolf at night and can't control it ! Not sure it make sense though as I haven't follow Blood in BG.
In the PFH announcement picture the dead guy no longer has legs. Definitely something a werewolf coulf have done.
This seems like a very plausible theory. I've only read a little of BiBG but when I have time I will check it out with this theory in mind. I can say that it is set a few years before BG3 starts. It may well be someone with a completely uncontrolled lycanthropy curse, who suddenly is able to control it thanks to the tadpole.
Edit: I've tried to pick up BiBG, and the evidence seems to point to an evil (male human?) sorcerer, not a random werewolf. It is perhaps the third villain, not the seventh origin.