I am pretty sure that Randall Forrester is the cannibal and i think he lives right outside of Armadillo in the hills somewhere,i got some of the info from the newspaper in the trailer,And i am pretty sure that Nigel West Dickens survived a hanging at some point in his life he appears to have a nasty scar across his neck.
I really like the cannibal aspect of the game, makes it seem really eerie when your riding around in the night, something that was missing from GTA in my opinion.