There are cooperating witnesses, and then there are cooperating witnesses.
More light was shed Tuesday on the nature of Marcello's cooperation with federal authorities in the case of John Ambrose, the deputy U.S. marshal accused of leaking critical information about a star witness in the Family Secrets case to the Outfit.
While it's clear from a defense filing that Marcello, the half-brother of one-time Chicago Outfit boss James Marcello, has been talking to prosecutors about what he knows about Ambrose, he's not going to willingly take the stand.
Prosecutors in court made clear to the judge that Marcello was going to be giving testimony under a grant of immunity, essentially forcing Marcello to take the stand and testify.
Ambrose is accused of leaking information about mob hitman turned federal witness Nick Calabrese to a friend with mob ties, and the information made its way to the Marcellos.
James Marcello was worried about what Nick Calabrese was telling investigators because both men had taken part in the mob murders of Anthony and Michael Spilotro.
Michael Marcello pleaded guilty in the Family Secrets case, while James Marcello was convicted at trial.
Expect Ambrose's defense attorney, Frank Lipuma, to grill Michael Marcello about what Lipuma has described as conflicting accounts on what Marcello has told investigators.