Brother of Mob Boss to Testify Against U.S. Marshal

For months, Michael Marcello passed along key information about a top mob snitch during his 2003 prison visits to his half-brother, James "Little Jimmy" Marcello -- the Chicago Outfit's top boss.

The details about the key witness, mob killer Nicholas Calabrese, were allegedly coming from the man assigned to protect Calabrese from the mobsters who wanted him dead -- deputy U.S. Marshal John Ambrose.

Now, in a stunning reversal, Michael Marcello, once his imprisoned half-brother's eyes and ears on the street, will testify against Ambrose next month, a prosecution filing shows.

Ambrose is charged with leaking important information about Nick Calabrese to the Outfit. Marcello could provide key testimony about how the information allegedly made its way from Ambrose to Ambrose's friend with Outfit connections to reputed mobster John "Pudgy" Matassa to Michael Marcello to James Marcello. Matassa has not been charged in the case.

Michael Marcello pleaded guilty in the Family Secrets case in June 2007, admitting he ran an illegal video-poker business. He didn't agree to cooperate then and got 8½ years in prison.

It's unclear what prompted the turnaround. Prosecutors would not comment, and an attorney for Marcello did not return a message. Such cooperation often results in less prison time.

Prosecutors secretly recorded Michael Marcello's conversations when he visited James Marcello in prison.

The Marcellos were intent on finding out what Nick Calabrese had revealed about James Marcello's involvement in the 1986 killings of mobsters Anthony and Michael Spilotro.

James Marcello drove the Spilotros to a Bensenville area home, where the two men believed they were going to get promotions in the mob, according to testimony in the Family Secrets case. Instead, several mobsters, including Nick Calabrese, pounced on them and beat them to death.

Thanks to Steve Warmbir