Did US Marshall Put Flipped Mobster at Risk?

In a brief but loud confrontation, the top FBI agent in Chicago, Robert Grant, underscored the deadly potential of a deputy U.S. marshal leaking information to the Chicago mob about a star government witness, as Grant verbally battled with the deputy marshal's attorney during a court hearing on Monday.

"This leak put at risk the most important witness in the Family Secrets case. It put at risk the agents guarding him. It put at risk his wife," Grant said, during questioning by Francis C. Lipuma, the lawyer for U.S. Deputy Marshal John Ambrose. "This leak was no small leak."

Ambrose is accused of leaking information about mob hit man Nicholas Calabrese, the star witness in the Family Secrets trial, which ended in September with the convictions of five defendants, including Calabrese's brother, mob killer Frank Calabrese Sr.

Chicago mobsters "protect their own because it's assumed they won't cooperate. Once that cooperation becomes known, it's fair game," Grant said.

A federal judge is holding a hearing to determine what statements by Ambrose, if any, should be allowed at his trial.

Ambrose contends when he was lured to FBI offices in September 2006 on a ruse, he was in custody but not initially read his Miranda rights.

Both Grant and U.S. Attorney Patrick Fitzgerald, who paired up to talk with Ambrose initially, testified at the hearing that they told Ambrose he wasn't under arrest.

Ambrose's name came to light during secret FBI recordings of Chicago mob boss James Marcello while in prison.

Grant said that Ambrose admitted he knew two of his friends had connections to mob bosses Joseph "Joey the Clown" Lombardo and John "No Nose" DiFronzo.

Thanks to Steve Warmbir