At about age 20, Greig married Robert "Bobby" McGonagle, a Boston firefighter. He was from a family that led the Mullen Gang and was injured during a mob gunfight in 1969. Before his 1987 death by drug overdose, McGonagle reportedly held Bulger responsible for the murders of his brothers, twins Donald and Paul McGonagle, who were killed during fighting between the Mullen-Killeen gang war. The body of Paul McGonagle, of whom Greig's sister Margaret was a widow, lay hidden and buried for 25 years on Tenean Beach in Dorchester. Greig's younger brother David, a close associate of Bulger, was found shot dead on Cape Cod in an apparent suicide.