Just like Lou Para says, there´s absolutely no prove of Oswald being a KGB agent. Neither are there any prove of Oswald being a communist/marxist/stalinist (whatever) in his KGB files handed to Clinton by Yeltsin. I think you are jumping to absurd conclusions.

http://www.paperlessarchives.com/FreeTitles/OswaldKGB.pdf

An article published in the Russian newspaper Commersant (June 22, 1999) dealt with Oswald´s KGB files. Hit "Translation" right under the article. http://www.jfk-info.com/russian1.htm

Retired KGB colonel Mikhail Lyubimov told Echo Moscow radio station that the assassination of President Kennedy sent Soviet leaders into shock and left Moscow fearful that it would be blamed for the murder. "(Nikita) Khrushchev rushed in terror to the U.S. ambassador to say we were not involved," Lyubimov said of the then Soviet leader. "The only sensation that will hit the world (following release of the latest documents) is that we (the Soviet Union) had nothing to do with the assassination of Kennedy," he said. "I rule it out 100 percent. Even under Stalin we didn't assassinate foreigners and after his (Stalin's) death the politburo banned terrorist acts," Lyubimov said. He dismissed suggestions that a rogue KGB unit could have gone in alone and carried out the operation, saying "the KGB was strictly under the control of the politburo and the party leadership."

In 1962, Oswald left the Soviet Union and returned to the USA. He encountered none, whatsoever, problem with reentering US. He even got his American citizenship back without breaking a sweat. And that´s remarkable considering being an American "defector" and self proclaimed "marxist". Oswald being a marxist...are you serious? Keep in mind that this was in the midst of the cold war. At that time, people were jailed in the US for just sympathizing with socilasm. Read about the McCarthy era for example. One of Oswald´s best friends in Dallas was George De Mohrenschildt, a Belo russian immigrant so far to the right on the political scale, you would have to turn your head 180 degrees to be able to see him. It was through his contacts, Oswald gained a job at the school book depository in Dallas. Find out about George De Mohrenschildt by googling him. Do you really think De Mohrenschildt would have helped Oswald if Oswald was a communist/marxist/leninist? Of course not!

I think, if you really want to find out who killed JFK, do some heavy research on United States National Security Council and some of its members at the time of the JFK killing. Was the Mafia somehow involved? Maybe, who knows?