After prosecutors declined to press charges a third time, Mr. Carter was finally free and moved to Toronto to live with the commune and Mr. Martin. He married commune leader Lisa Peters, but by the early 1990s, the marriage crumbled. He then broke with the commune, bucking at its control over him after so many years in jail. Friends say he needed to stand on his own two feet. He also struggled with alcohol, a substance the commune did not allow.
He moved in with Mr. Martin, then attending university, and the younger man was amazed at how out-of-touch nearly 20 years of incarceration had left Mr. Carter. He had never used voice mail, Mr. Martin said, or a bank machine. A passionate, preacher-like orator, Mr. Carter made money on his speaking engagements.
Before he broke with the commune for good in the early 1990s, Mr. Carter and the Canadians got involved in the beginnings of the Association in Defence of the Wrongly Convicted.
Toronto lawyer James Lockyer was fighting to free Guy Paul Morin, a Toronto-area man wrongly convicted of raping and murdering a nine-year-old girl, and Mr. Carter and the commune also got involved.
Mr. Carter would become the association’s executive director. For the next 11 years, he was the front man for its efforts to free those jailed for crimes they did not commit. He and Mr. Lockyer would become close friends.
Mr. Lockyer remembers getting a call from Mr. Carter in 1999, when the ex-boxer was with Bill and Hillary Clinton in the White House for a special screening of Hurricane, the film by Canadian director Norman Jewison. Mr. Carter wanted to know if he should lobby the president to intervene in the case of a woman on death row in Vietnam that the association was trying to help.
But in 2004, Mr. Carter would resign from the association in anger, and break off all contact with Mr. Lockyer. He had demanded that the association do more to protest the appointment of the prosecutor behind Mr. Morin’s conviction as a judge
Fire would consume Mr. Carter’s rented west-end house while he was on vacation that same year. He had no insurance, and was forced him to move to a basement apartment for a time.
He soon started his own small organization, Innocence International, to fight for prisoners he felt were wrongly convicted. And he wrote a 2011 memoir entitled Eye of the Hurricane: My Path from Darkness to Freedom, that featured a foreword by Nelson Mandela.
Mr. Carter was diagnosed with terminal prostate cancer in 2011. Mr. Artis, who had remained his friend ever since that night in 1966, dropped his life in Virginia to come to Toronto and care for Mr. Carter, after learning that his old friend was dying with no family at his side. He said Mr. Washington, whose portrayal of Mr. Carter was nominated for an Oscar, kept in touch, phoning Mr. Carter at Christmas time, for example.
Even as his health deteriorated, he sent a letter to the New York Daily News in February demanding the release of Brooklyn man David McCallum, whom Mr. Carter said was wrongly convicted of murder and jailed in 1985 -- the year he was released -- with no evidence.
“I am now quite literally on my deathbed and am making my final wish, which those in authority have the power to grant,” the letter reads, adding that Mr. Carter will be surprised if he sees heaven after his death. “To live in a world where truth matters and justice, however late, really happens, that world would be heaven enough for us all.”
Editors note: An earlier version of this article featured a headline that incorrectly spelled Mr. Carter's first name. This version has been corrected.