He spent five years (19711976) in the Attica Prison after a robbery conviction. While in prison, Brown converted to Islam and changed his name to Jamil Abdullah al-Amin. After his release, he opened a grocery store in Atlanta, Georgia and became a Muslim spiritual leader and community activist preaching against drugs and gambling in Atlanta's West End neighborhood.
He also became the leader of Ummah, "a group of mostly African-American converts to Islam, which seeks to establish a separate Sharia-law governed state within the United States."