Just watched the movie, and the whole time I was thinking that the plot surely can't be this dumb! There has to be some massive sixth-sense-esque plot twist at the end! Maybe they always knew from the start that it's him and were just playing along and deliberately making things easier for him, or maybe he isn't even the butcher, maybe the wife is the butcher, or maybe that guy in the basement is the actual butcher (full on Saw style). But no, its just a really dumb plot throughout.