Joan Shannon and the Sex Swinger Murders An Anthology of True Crime

WHEN YOUR FRIENDLY NEIGHBORHOOD 'SEX PARTY' TURNS DEADLY 
Joan and David Shannon were swingers who met other married couples for "sex parties" through the Internet. David would introduce his wife to Jeffrey WIlson and the two quickly fell in love. David grew jealous and warned his wife to stop seeing Wilson. 

Joan, however, wanted to keep seeing her swinger friend. In a bizarre series of events, she enlisted the aid of her fifteen-year-old daughter Elizabeth to kill David.