"While I'm not sure he was murdered, if he was, it would have been more likely that his assassination was ordered by Truman or Eisenhower"
Did they also plan the assassination of John Wayne - I think your letting Stalin off way too easy.
http://news.bbc.co.uk/1/hi/world/americas/3114963.stm
Stalin had his tit in the wringer with 50000 allie hostages and he knew that Patton would demand justice and a rescue.
This would have crushed Russia - he had a lot more to lose than some US politician.