According to authorities the last known individuals to see Giancana alive were Chuckie English and Butch Blasi. It's possible someone else did visit him, but these two names are the ones listed in newspapers and by LE. Names such as Tony Spilotro and others have been mentioned, but no evidence seems to exist that ties them to the murder.

Here's a link to the Tribune story. Be sure to go to page 5 and read the entire story.

http://archives.chicagotribune.com/1975/06/21/page/1/article/cops-watching-home-night-giancana-slain