I for one, believe the Marcello/JFK tie. Do I believe he told this dude in prison what happened when he had thousands of secrets? I doubt it, UNLESS he was already having his issues with dementia and Alzheimers as he did have those issues before they let him out. I forget the timeline he started having the issues though, but if I remember correctly he was caught over the phone saying something about buying a judge or juror or something with someone from the Los Angeles family as well.

Yes Robert Kennedy had Marcello removed from the country when he was supposedly making all of his check ins due to the immigration issue. So he checks in one day and they put him in cuffs and he disappears. That sealed JFK's fate for sure.

Also on Ruby, his girls used to go to NOLA and dance plus Ruby was loosely tied to the Dallas family in which Marcello did business with as well.