A controversial figure from the 1971 inmate uprising at the Attica State Correctional Facility has died in an apparent accident near an isolated village in British Columbia.

An investigation into the death of John Boncore – a former Buffalo resident who was known as John B. Hill during his days as an Attica prisoner – has turned up no evidence of foul play, officials of the British Columbia Coroners Service said Sunday.

Royal Canadian Mounted Police who investigated the death told the Kamloops Daily News that the 61-year-old Boncore’s body was found March 12 on a hiking path on the Adams Lake Indian Reserve, not far from his home in the small village of Chase, B.C.

Police said they believe Boncore, a Mohawk Indian, may have slipped and fallen on some cement steps, causing a fatal blow to the head.

Boncore, then known as Hill, became one of the most controversial figures associated with the September 1971 Attica prison rebellion, the bloodiest prison riot in American history. Thirty-nine people were killed, including 10 prison employees and 29 inmates.

Boncore was the only prisoner convicted of murder for his actions during the riot. He was convicted of the fatal beating of William E. Quinn, a state corrections officer, at the outbreak of the riot.

During a 1975 trial where he was represented by famed defense attorney William M. Kunstler, Boncore denied attacking Quinn. Several prosecution witnesses testified that they saw Boncore strike the fallen Quinn with a two-by-four, but defense witnesses said Boncore was attacked by other inmates.

Despite Kunstler’s claims that Boncore was the victim of a government frame-up, a State Supreme Court jury in Buffalo convicted Boncore of murder, and he was sentenced to at least 20 years in prison.

In December 1976, another controversy erupted when then-Gov. Hugh Carey pardoned Boncore and seven other inmates who were convicted of crimes during the riot. The governor also dismissed possible disciplinary actions that were pending against 20 law enforcement officers who were involved in the violent retaking of the prison.

The pardon of Boncore enraged officials of a state union representing corrections officers.

“I think the governor did the right thing in pardoning John,” said Sharon Fischer, a longtime activist from the City of Tonawanda who knew Boncore in the 1970s. “I don’t believe that John did kill Officer Quinn.”

Fischer is a legal assistant who helped Boncore and many other former Attica prisoners with their legal problems after the rebellion. She said she met Boncore around 1972, when he was facing the murder charge.

“He was a mixed-up, messed-up kid. He told me he grew up bouncing from one foster home in Buffalo to another,” Fischer said in an interview Sunday night.

After he got out of prison, Boncore became an outspoken activist for peace and civil rights, Fischer said.

He moved to Canada, where he became active in a number of causes. In March 2009, he made headlines in Calgary, Alberta, when he was arrested for trying to make a “citizen’s arrest” of former President George W. Bush for alleged war crimes. The incident made Boncore a hero among peace activists.

Boncore was also known in British Columbia for organizing native American protests of a proposed oil pipeline project.

“He became a very outspoken activist for good causes after his experience at Attica,” Fischer said.

She added that she hopes Canadian authorities will continue their investigation to make certain that Boncore was not a victim of foul play.