Here is an anniversary piece from last year in
The Atlantic magazine with Castro trying to erase himself from the wider picture. I particularly like the bit where the sympathetic interviewer intimates that Castro felt sad Kennedy died so young. This would be the same Castro who pleaded with Khrushchev to bomb America at the time of the Cuban Missile Crisis. Fidel, you will be pleased to note, now has second thoughts about his moment of millennial psychosis: "After I've seen what I've seen, and know what I know, it wasn't worth it at all." Well, that's okay then! Here Castro offers the results of his own secret police's active-research on the assassination, which once and for all rules out Oswald as the assassin. I am surprised Oliver Stone, Castro's good buddy, did not use their highly scientific conclusions for his film:
http://www.theatlantic.com/international/archive/2013/11/castro-oswald-could-not-have-been-the-one-who-killed-kennedy/281674/2/
Here is the article I wrote last year, "What JFK's Assassination Did to America", published in the November 2013 edition of
Quadrant on the 50th anniversary of the assassination. Not being one for conspiracy, I wouldn't accuse Castro of organising the assassination of JFK, although it is fascinating to speculate on Lee Harvey Oswald's movements in the aftermath of murdering Kennedy - Oak Cliff was on the bus route to the nearest airport. This, of course, does not implicate Castro in any direct way:
https://quadrant.org.au/magazine/2013/11/john-f-kennedys-assassination-america/