Boy, you've brought up a good question. What would have happened if Giancana had been subpoenaed to appear before a Senate Committee? He could not be prosecuted, but would he have to answer questions before a congressional committee? His agreement was with the state of Illinois. I read that Giancana's immunity agreement was presented to several courts, maybe the Illinois Supreme Court ( not sure, maybe), before Hanrahan got the green light that it was legal. I'm wondering if Giancana's willingness to answer questions and immunity agreement would have kept him from being indicted. And if he's not indicted, i would venture to guess that his testimony would be sealed. Now how in the world would that be handled by a Senate Committee ? I'll work on this......may take a few days.