Katyn Revisited

A recent AP News story headlined, Memos show US hushed up Soviet crime, by Randy Herschaft and Vanessa Gera.
The gist of the article was that it appears that the US government might have had some credible evidence during the war about the Russian massacre of Polish POWs that took place on the orders of Stalin.
American and British POWs views the site of the massacre (Germans took them there and made then inspect the site to prove that it was the Russians who carried out the killings.)   It is unclear exactly at what level of the US government the information stopped and was not passed on (It is not clear what really could have been done, although one could argue it might have given Roosevelt and his key advisers a different appreciation of Stalin when it cam time to meet at Yalta.  Perhaps, the history of Eastern and Central Europe might have been different, but that remains problematic as the Red Army was already there.).  I would like to review the documents, when they do become available, to see if we can identify what exactly what level of the government the information stopped.
Now the other issue that I have is the reluctance of the US government (despite what Congress concluded in 1952) to assert the guilt of the Russians until the 1990s.  Sometimes political correctness goes too far.
I have course materials available on Katyn.