Task: Question Generation
Input (English): Context : Margie Velma Barfield (née Margie Velma Bullard) (October 29, 1932 -- November 2, 1984) was an American serial killer, convicted of one murder, but she eventually confessed to six murders. 
Subject : Velma Barfield 
Relation : convicted of
Output (English): Which crime led to the conviction of Velma Barfield?