Clemenza?

During the GF2, Fredo says Clemenza died of a heart attack, and Cicci speaks out saying that wasnt no heart attack. What do you think happened to Clemenza?

Santo, there have been many discussions on this topic. Here is the link to the most recent one:

http://www.thegodfathertrilogy.net/ubb/ultimatebb.php?ubb=get_topic;f=1;t=004516#000000