S4·E17 The Fat Guy Strangler

Lois discovers she has a brother named Patrick and takes the family cross-country to meet him. It turns out; he’s locked up in a mental institution. Lois thinks he’s sane, so she checks him out to live with the Griffins. Meanwhile, Peter starts the Society for the Acceptance of Fat Men. But when all the fat men of Quahog are strangled one-by-one the group lives in fear. Who could the “Fat Guy Strangler” be?