Attica Uprising Figure's Death Ruled an Accident The death of the only inmate convicted of murder following the 1971 Attica prison uprising was an accident caused by alcohol and cocaine use, Canadian officials said Monday. The body of 61-year-old John Boncore was found March 13 in his home on the Adams Lake Indian Reserve in British Columbia. According to an autopsy report by the British Columbia coroner's office, Boncore had an enlarged heart, had recently used cocaine and had a potentially life-threatening blood alcohol level of more than 0.35 percent when he died. Boncore, a Mohawk Indian who was born in Buffalo, was known as John B. Hill at Attica when inmates took control of the maximum-security prison in rural western New York. Thirty-two inmates and 11 civilian employees died during the five-day siege, including 10 hostages and 29 inmates who died when state troopers stormed the prison's D Yard on Sept. In 1975, a state Supreme Court jury in Buffalo convicted Boncore of murder for the beating death of Corrections Officer William Quinn. He was sentenced to at least 20 years in prison. Boncore, who had denied attacking Quinn, was granted clemency in 1976 by then-Gov. Hugh Carey amid a probe of the state's handling of the uprising. Carey also pardoned seven other inmates convicted of crimes during the riot and dismissed pending disciplinary actions against 20 law enforcement officers. The coroner's report said witnesses saw Boncore purchase 24 beers throughout the day on March 11. He was last seen alive that night when a taxi drove him home from a known drug house, the report said. The taxi driver reported Boncore fell down the steps to his basement apartment, but said he was fine and went inside. The autopsy, which concluded Boncore died early on the morning of March 12, showed no significant injury and no sign of foul play.