Brown — who later in life changed his name to Jamil Abdullah Al-Amin — died Sunday at the Federal Medical Center in Butner, North Carolina, his widow, Karima Al-Amin, said Monday.

A cause of death was not immediately available, but Karima Al-Amin told The Associated Press that her husband had been suffering from cancer and had been transferred to the medical facility in 2014 from a federal prison in Colorado.

Like other more militant Black leaders and organizers during the racial upheaval of the late 1960s and early 1970s, Brown decried heavy-handed policing in Black communities. He once stated that violence was “as American as cherry pie.”

“Violence is a part of America’s culture,” he said during a 1967 news conference. “… America taught the black people to be violent. We will use that violence to rid ourselves of oppression, if necessary. We will be free by any means necessary.”

Brown was chair of the Student Nonviolent Coordinating Committee, a powerful civil rights group, and in 1968 was named minister of justice for the Black Panther Party.

Three years later, he was arrested for a robbery that ended in a shootout with New York police.

While serving a five-year prison sentence for the robbery, Brown converted to the Dar-ul Islam movement and changed his name. Upon his release, he moved to Atlanta in 1976, opened a grocery and health food store and became an Imam, a spiritual leader for local Muslims.

“I’m not dissatisfied with what I did,” he told an audience in Kansas City, Missouri, in 1998. “But Islam has allowed things to be clearer. … We have to be concerned about the welfare of ourselves and those around us, and that comes through submission to God and the raising of one’s consciousness.”

On March 16, 2000, Fulton County Deputy Sheriff Ricky Kinchen and deputy Aldranon English were shot after encountering the former Black Panther leader outside his Atlanta home. The deputies were there to serve a warrant for failure to appear in court on charges of driving a stolen car and impersonating a police officer during a traffic stop the previous year.

English testified at trial that Brown fired a high-powered assault rifle when the deputies tried to arrest him. Then, prosecutors said, he used a handgun to fire three shots into Kinchen’s groin as the wounded deputy lay in the street. Kinchen would die from his wounds.

Prosecutors portrayed Brown as a deliberate killer, while his lawyers painted him as a peaceful community and religious leader who helped revitalize poverty-stricken areas. They suggested he was framed as part of a government conspiracy dating from his militant days.

Brown maintained his innocence but was convicted in 2002 and sentenced to life.

He argued that his constitutional rights were violated at trial and in 2019 challenged his imprisonment before a U.S. Circuit Court of Appeals. In 2020, the U.S. Supreme Court declined to take the case.

“For decades, questions have surrounded the fairness of his trial,” his family said Monday in a statement. “Newly uncovered evidence — including previously unseen FBI surveillance files, inconsistencies in eyewitness accounts, and third-party confessions — raised serious concerns that Imam Al-Amin did not receive the fair trial guaranteed under the Constitution.”