Even after his appointment to the Supreme Court, Frankfurter remained close to Roosevelt. In July 1943, on behalf of the President, Frankfurter interviewed Jan Karski, a member of the Polish resistance who had been smuggled into the Warsaw ghetto and a camp near the Belzec death camp in 1942, in order to report back on what is now known as the Holocaust. Frankfurter greeted Karski's report with skepticism, later explaining: "I did not say that he was lying, I said that I could not believe him. There is a difference."