Yes they made a major step forward but they could not come out with the “whole truth” and that is that Carlos Marcello and Carlos Trafficante conspired together to kill JFK. This in conjunction with Hickey accidentally firing the, or one of the head shots that killed JFK.
Marcello and Trafficante both admitted that they did it. Marcello made insinuations, found in the book "Mafia Kingfish" and another book?? That he did it and while in prison he admitted it to his cell mate who was an FBI plant that “they” did it. Trafficante admitted to his lawyer Frank Ragano while in a car with him. That is in Ragano’s book "Mob Lawyer". Trafficante admitted it just before he passed away.
There was also another time that Trafficante told someone that JFK was going to be hit.
As you know, we don't agree on the Hickey shot, but I totally agree that elements of the Mafia were involved.
I concur that John Davis's book
Mafia Kingfish is a great book. An even better book on the Mafia angle, perhaps the best book on the subject, is Dr. David Scheim's book
The Mafia Killed President Kennedy (previously titled
Contract on America).
Believe it or not, another good book on the Mafia angle is Robert Blakey and Richard Billings' book
Fatal Hour: The Assassination of President Kennedy by Organized Crime.