BOSTON — Francis “Cadillac Frank” Salemme, the once powerful New England Mafia boss who was serving a life sentence behind bars for the 1993 killing of a Boston nightclub owner, has died at the age of 89, according to the Bureau of Prisons. Salemme died on Tuesday, according to Bureau of Prisons’ online records. After being released from prison, Salemme was seriously wounded in a shooting outside a suburban Boston pancake house.