Chicago mobster Frank Calabrese Sr., a hit man who strangled victims and then slashed their throats to be sure they were dead, has died in a federal prison in North Carolina, authorities said.
Calabrese, 75, died on Tuesday at the Butner Federal Medical Center, said Ed Ross, a spokesman for the Federal Bureau of Prisons.
Ross had no information on the cause of death, though Calabrese claimed at his sentencing in 2009 that he suffered from a host of ailments, including an enlarged heart.
Calabrese was among five men convicted in September 2007 at the Family Secrets trial, which resulted from a major, multiyear effort by the federal government to weaken the Chicago Outfit, as the city's organized crime family calls itself.
The investigation also was aimed at clearing 18 unsolved mob murders dating back to the early 1970s. Calabrese was blamed for thirteen of them, a jury found him responsible for seven of them, and he was sentenced to life in prison.