A former leader of the radical Black Panther movement in the United States who was wrongfully imprisoned for 27 years has died.

Family members of Elmer Pratt say he died Thursday in a small village in Tanzania where he had been living. He was 63.

The cause of death is not clear.

Pratt, whose nickname was “Geronimo,” was convicted in 1972 for allegedly robbing and killing a woman in California.

He long maintained his innocence and said he was targeted by the FBI because he was a member of the Black Panther movement.

Pratt's conviction was overturned in 1997, and prosecutors announced two years later they would not seek to retry him.

The Black Panther movement, which was active in the U.S. from 1966 to 1982, was an African-American leftist revolutionary organization. The movement sometimes used violent means to fight what it considered police brutality.