Cicci had been told to "wait in the car" by Frankie before the fateful meeting with the Rosatos at Richie's bar. After the cop busted up Frankie's murder, there was a shootout outside the bar. The last we saw of Cicci before the Senate hearing, he was shooting, probably had been shot, and was knocked over by a huge '57 Lincoln Capri. The man had been seriously hurt.
No doubt he was picked up by police on the scene, and could have been charged with a number of felonies that were related to the gunplay in that scene alone, never mind any crimes that might have been pending against him previously. But when Frankie turned state's evidence, Cicci (or more likely, his lawyer) would have figured out that the best thing for him would be to do likewise, rather than have to face charges related to the street shooting, or be implicated in anything Frankie was blabbing about.