Leccisi died Sunday at a retirement home in Milan after a battle with heart and respiratory problems, his son Gabriele said Monday.
In 1946, Leccisi and two other Italians marked the anniversary of the death of "Il Duce" by digging up Mussolini's body at night from an unmarked grave in a Milan cemetery. The theft sparked a nationwide manhunt for the group.
The three entrusted the body to two monks who buried it at a monastery near the northern city. Authorities located the remains there and returned them to the family years later for burial in Predappio, Mussolini's birthplace.
Leccisi was sentenced to six years in jail for stealing the body but benefited from an amnesty passed for some Fascist-era crimes, his son said. He worked as a right-wing journalist and later served as a lawmaker with a neo-Fascist party in the 1950s and 1960s.