Karla Homolka

Team sexual predator with husband Paul Bernardo. Lured four 
adolescent girls to be his sexual slaves, then participated 
in their rape torture and murder. One of them was her baby sister.  
Karla's sister Tammy died while Karla was sexually molesting her. 
Karla only got twelve years for this, because she was allowed to 
plea-bargain and testify against husband Paul before prosecutors
knew that her sexual murder of her sister was caught by the couple 
on film. She could be out in four more years.

http://www.crimelibrary.com/serials/bernardo/bernmain.htm

http://tanadineen.com/COLUMNIST/Columns/Homolka.htm

http://www.loveanddates.com/paul_bernardo_and_karla_holmolka.htm

http://directory.google.com/Top/Society/Crime/Murder/Serial_Murder/Serial_Killers/Aliases/Ken_and_Barbie_Killers/