In 1939, four months before the start of World War II, Jewish men, women and children were denied entry to the US from the MS St Louis, sent back to Europe and many then died in the Nazi death camps.

The President who denied their entry was Franklin Delano Roosevelt. 

 He also was aware of the deaths being conducted by the Nazis in 1942,  long before they were liberated and chose to prosecute the war instead of taking any other action to save them. or stop their operation by bombing them.  

https://en.wikipedia.org/wiki/Auschwitz_bombing_debate

The California Attorney General who was in charge of sending the Japanese to our concentration  camps during WW II was later Governor of California (3 times) and Chief Justice of the United States Earl Warren.  Brown v. Education?  Miranda v. Arizona?

Both of these paragons of virtue were elected by the people.  Neither was a dictator.  One was a Democrat, one was a Republican.