FDR had eyewitness accounts:
Former Mayor Ed Koch and Polish dignitaries honored the life of Jan Karski before a crowd of about 150 who gathered on Poland's Independence Day.
Karski, a Catholic member of the Polish Underground, repeatedly risked his life and was imprisoned and tortured as he tried to inform the world about the Jewish genocide occurring in the Nazi concentration camps.
"He tried desperately to save the Jews in Europe, and, unfortunately, FDR didn't listen," said Koch. "It was sad because we're reflecting on the deaths of about 6million Jews, and joyous because we're reflecting on the glory of a hero."
FDR was an anti-semite. He could have cared less about the holocaust or the Jews, IMHO.