Yeah, he signed an affidavit, but it seems to have been largely under duress. He was charged with Murder One, Possession, Bookmaking, probably set up on those charges by Roth's people (He shows disdain for drug dealing earlier in the film, so I believe the drug charge was trumped up), and he and Cicci were convinced and misled into believing that Michael had them him up to be killed, basically betraying them to Hyman Roth for no reason despite years of loyal service--Selling their own Sicilian blood out to a "Jew in Miami".

Yes, he signed an affidavit, but when it came time to testify he didn't--Thus rendering his affidavit worthless and he claimed to not even really know Michael and that everything he told the FBI people was a lie. His testimony as it were actually HELPED Michael in that it destroyed the credibility of the case. It made the Senate's case look like a joke, a sham, that the Senate

I just think given the circumstances and the way ALL of them were played by Roth, he and Cicc' should've been given a pass. They were set up. They didn't go with the Feds out of malice, but to survive, under duresss: Either be killed by Michael (so they thought) or killed by the Rosato Brothers. Given the circumstances both likely felt there was no safe place left on the streets for them.