CHICAGO -- The star witness in the government's case against a dozen Chicago mob figures pleaded guilty Friday to taking part in a conspiracy that included 18 murders, including hits on Anthony "The Ant" Spilotro, long known as the Chicago mob's man in Las Vegas, and Spilotro's brother, Michael Spilotro, in 1986.
Under heavy security, Nicholas Calabrese admitted that he took part in planning or carrying out 14 of the murders, including the Spilotro killings.
The husky, white-haired Calabrese is expected to be the key witness against his brother, Frank Calabrese Sr., and other major mob figures charged in the government's Operation Family Secrets investigation. That trial is expected to begin this summer.
The investigation was aimed at clearing up old, unsolved gangland killings and bringing down Chicago's organized crime family.
James Marcello and Joseph "Joey the Clown" Lombardo, both reputed to be major mob bosses in the Chicago area, are among the 12 defendants. They have pleaded not guilty and are detained pending trial.
Husky federal marshals scanned the spectator seats as Calabrese entered his plea.
A federal marshal who was assigned to guard Calabrese at one time, John Ambrose, now is charged with leaking information concerning Calabrese's whereabouts to organized crime. He has pleaded not guilty.
Calabrese said little at the hearing. But when U.S. District Judge James Zagel asked what he did for a living, he said: "Aside from illegal activities, I was a rigger at McCormick Place," the large exposition hall on Chicago's lakefront south of downtown.
In his signed, 16-page plea agreement, Calabrese admitted he was a member of the 26th Street or Chinatown Crew of the Chicago mob and took orders from his brother in carrying out an array of criminal activities.
He said that included collecting debts for loan sharks.
His plea agreement said the murders he took part in were sometimes "committed in order to protect the Outfit from individuals who were providing information about the enterprise to law enforcement officers."
The Chicago Tribune has cited law-enforcement sources as saying Calabrese agreed to cooperate after he was confronted with DNA evidence linking him to at least one murder.
The Spilotros were beaten to death and buried in an Indiana cornfield. Joe Pesci played a character based on Tony Spilotro in the movie "Casino."
Calabrese could be sent away for life for his guilty plea to a charge of racketeering conspiracy. Zagel noted Friday that Calabrese could face at least 24 years in prison according to federal guidelines. But in exchange for his cooperation, federal prosecutors have agreed to recommend a sentencing break for Calabrese.
They have not said how much of a break he might get.
After entering his plea, Calabrese was whisked out a rear door of the courtroom by marshals. He is being held in an undisclosed location to keep him safe from mob reprisals.