After a 1956 Commission meeting, the crime families of Philadelphia, headed by Angelo Bruno, and Detroit, headed by Zerilli, were added to The Commission. As a commission member Zerilli acted as a senior L.C.N. leader alongside the five New York City bosses and other top Mafia bosses from around the country at the time that included Stefano Magaddino of Buffalo, Sam Giancana of Chicago, Angelo Bruno of Philadelphia, Santo Trafficante Jr. of Tampa, Carlos Marcello of New Orleans and Raymond Patriarca Sr. of New England. Joe Zerilli remained the top boss of the Detroit Mafia until his death of natural causes on October 30, 1977, at the age of 79.