Billy Ray Hamilton was born on January 31, 1949. Details about his early life are scarce, but his criminal activities eventually led to his incarceration at Folsom State Prison in California. While serving time, Hamilton met fellow inmate Clarence Ray Allen. Allen, already serving a life sentence for orchestrating the 1974 murder of Mary Sue Kitts, befriended Hamilton and allegedly offered him $25,000 to eliminate eight witnesses who had testified against Allen. Allen referred to Hamilton as his "good dog," indicating a manipulative relationship.

After being paroled from Folsom Prison, Hamilton, accompanied by his girlfriend Connie Barbo, carried out Allen's orders. On September 5, 1980, they went to Fran's Market in Fresno, California, where one of the witnesses, Bryon Schletewitz, worked. Hamilton murdered Schletewitz and fellow employees Josephine Rocha, 17, and Douglas White, 18, with a sawed-off shotgun. He also wounded two others, Joe Rios and Jack Abbott. Hamilton was wounded during the incident but managed to escape. Five days later, he was arrested while attempting to rob a liquor store. At the time of his arrest, he was found carrying a "hit list" with the names and addresses of witnesses who had testified against Allen.

Hamilton was convicted on three counts of first-degree murder with special circumstances, one count of attempted robbery, and two counts of assault with a deadly weapon. He was sentenced to death on March 2, 1981. His death sentence was reversed in 1985 but reinstated on July 28, 1988. Hamilton died of cancer on October 22, 2007, while on death row at San Quentin State Prison.