The Chicago Sun-Times reported Tuesday that Muhammad, the son of Nation of Islam founder Elijah Muhammad, died at the University of Illinois at Chicago Medical Center just days after undergoing open-heart surgery.

A longtime Chicago resident, Muhammad managed Ali's career from 1966 until 1981, and continued to work for Ali during his post-boxing career until 1991. Muhammad was also an advisor to his father, and served as the Nation of Islam's business manager while overseeing the organization's newspaper.