Motive might have been to steal the victims' money and any valuable possessions on them. Or perhaps that was simply their way of dealing with guests who offended them. Escape-wise, they had experience with respect to being elusive, and the whole deceptive identity toolkit. The outlaw colony was already on their radar. Escape https://en.wikipedia.org/wiki/Bloody_Benders#Escape Speculation was that the family members weren't related at all, but were two couples who banded together as a cover. Thus, it could remain unknown whether Kate was really into incest or not, as she claimed. The Colt Family of Australia was already multi-generation deep into inbreeding, but were at least not hillbilly butchers of humans. Attribute that caricature to faux families like the Benders, I guess.
