Not sure of Marcello involvement , I'm sure he played a lower role, money , guns , maybe a shooter and/ or a couple trusted guys to help

The reality is someone in intelligence was running Oswald

So he defects to Russia after serving at one of the most classified bases in the world . The one in Japan that secretly flew U2s over Russia and Oswald was a radar operator for these flights so had a lot of info to share . Mind you 6 months after his defection a U2 went down and a radar operator would of been key to help with that knowing flight paths, radio frequencies etc.

The the state dept gives him $1500 to come home with zero repercussions , the guy should have been hung for treason , right there you know he is being protected and / or used . Then he is placed with CIA assets like George M and The Paines who are strong anti communists , they were his babysitters .

You want to find out who whacked JFK , just backtrack who impersonated him in his calls to Russia and Cuban consulates in Mexico City . There is a reason the Warren Commission stays as far as possible from Mexico City as that is where the action is at . Anyway many have a good sense who helped here, the big question is who were the sponsors, if any , who gave the nod .

Guys like Dulles probably, maybe some big defense contractors, Texas oil men . Remember in those days the CIA was basically a front for business interests . Nobody gave a crap about Cuba until they nationalized big business interests. That's the real reason the USA felt communism was so dangerous , not the politics part but the money part, big companies losing if assets

Either way a big clue on who sponsored JFK hit , is who benefited the most and that was certainly big foreign policy makers that right after his death changed most of JFKs policies in Cuba, Russia , parts of Asia and the Middle East where he was working on a balanced approach , if his policies were fully implemented , I think things could be different now .

He was by no means a perfect man , had flaws , but when it came to foreign policy he was a damn genius , keeping is out of at least 3 wars , not too mention almost single handily keeping us out of nuclear one and oh boy did not invading Cuba in 62 piss off high military men plus the promise not to invade Cuba . Then the anti nuclear treaty right after , geez the war people were beyond pissed and the the American university speech in June was probably the last straw . It wasn't only Dallas , he was being hunted in many cities, especially Chicago and Tampa - in Chicago they caught the shooters but buried and destroyed the report .

A 2nd term was never going to happen