The general consensus is that Butch Blasi was the shooter. There are those who believe Chuckie English or Tony Spilotro were responsible for the murder. Since no one was every charged, it cannot be said for certain who actually killed Giancana. Some theorists say the CIA was responsible. But the majority of informed sources say it was Blasi.

There are reports that shortly after Giancana was killed, Blasi was observed chauffeuring Accardo around town. Could have been a reward for taking care of Giancana. Just my opinion.