Terry Davies was the father of Ryan Davies, who was kidnapped, raped, and murdered.
When the prime suspect was identified as Bill Turbit, a registered sex offender, Terry shot him to death outside a courthouse after an initial civil commitment hearing to determine whether Turbit should be sent to a mental institution. Ryan's real killers, two teenage boys named Jimmy G. and Mike D., were later arrested.
He was executed for Bill's murder. (SVU: "Uncivilized")