S04E17 Fat Guy Strangler
Lois discovers that she has a brother, named Patrick, that her parents have been keeping in a mental hospital for years. He seems perfectly healthy when she goes to see him, however, so she arranges for him to be released and come live with her family. Patrick was hospitalized over trauma at catching his mother in bed with Jackie Gleason, and Peter's appearance brings back the old memories, causing him to go on a killing spree of similarly fat men. Will they be able to convince Lois that her brother is behind all the killings before he gets to Peter?