confessed to it
https://pagesix.com/2009/01/06/jfk-assassination-confession/
Marcello later tells Ragano, “When you see Jimmy (Hoffa), you tell him he owes me, and he owes me big.” After JFK’s death, Marcello has enough “dirt” on Lyndon Johnson to make the new President forget about investigating anything that might lead to Carlos Marcello’s involvement in the assassination.