She realizes that Dr. Rigby would have seen this beforehand but did not mention it because he is the cannibal .
Meanwhile , Zack finds more marks on Ann Noyes 's sternum , which Brennan determines to be made by a sternum spreader .
Ann Noyes realizes that Dr. Rigby would have seen this beforehand but did not mention it because Brennan is the cannibal .
Meanwhile , Zack finds more marks on Ann Noyes 's sternum , which Brennan determines to be made by a sternum spreader .