The Murphy Twins are two drug trade dealers and hitmen responsible for the murder of Tricia Knowles, a recovered drug addict who had a baby boy named Austin and turned her life around. She crossed their employer, her ex-boyfriend Vance Dennis, by giving up his trade to the cops to try to get away from the underworld. As a result, she was overdosed and left to be found as a Jane Doe, left in a potter's field grave for months.
Tricia and Austin were recovered at her mother Sandra's insistence. The Murphy Twins' status remains unknown. (SVU: "Haunted")