Mutated from pockets of radiation and generations of inbreeding, these monstrosities attack anything on site that is not native to the swamp. They dwell in the deepest parts in the swamp all the way up to where Ashley's shop is located.
As always, an alpha emerges among a group, in this case, it happens to be a lunatic of a "man", George Lee, Oswald's older brother, who willingly exposed himself to radiation after being exiled from the Cabins:
Subject: Swamp Crazies 
Thu May 03, 2012 12:37 pm
