Any claim that they weren't watching a former Marine who had defected to the USSR, then come back to America, doesn't pass the smell test. But just because something smells rotten in Dallas doesn't lead to the conclusion that the spooks were backing Oswald.
“Any claim that they weren’t watching a former Marine who had defected to the USSR, then come back to America, doesn’t pass the smell test.”
Yes, they released his CIA 201 “pre-assassination” file, but it’s just full of documents about his defection or his return and some newspaper clippings, plus a few about his trip to Mexico in 1963 that was only picked up because the Mexico City embassy was under surveillance. I think they also released something about his debrief on his return from the Soviet Union, but I believe it was just a cover sheet and not the actual interview notes.
But as for documents that they did any surveillance or investigation of Oswald as a potential Russian asset now back in the US? Not one hint of anything like that. Perhaps all that would be in the FBI file, since they were charged with domestic counterintelligence. But then you have to wonder, exactly where is Oswald’s FBI file?