JFK. At the very least he was fascinated with Hitler.
Only 20 years after the war, it would've been so important to nail down the narrative, even more so than today. So I think they off'd him, because he was liked, respected, competent and therefore dangerous.
How JFK secretly ADMIRED Hitler: Explosive book reveals former President's praise for the Nazis as he travelled through Germany before Second World War | Daily Mail Online
JFK diary calls Hitler 'stuff of legends' - BBC News