Carol Mary Bundy

Recruited sexual victims for her boyfriend, then participated in their 
rape, murder, and sometimes decapitation. Between 6 and 50 victims.

Life, with possibility of parole.

http://www.crimelibrary.com/serial3/clark/
Book: "The Sunset Murders" by Louise Farr

http://www.amazon.com/exec/obidos/ASIN/0671700898/serialkillercent/104-4074935-4203167