As his plane circled the recently liberated Dachau concentration camp, Dr Leo Alexander could see the former inmates cheering and waving below.

They had good reason to cheer.

American Plains often brought food for the prisoners, like corn beef and potato salad.

The Plains also brought doctors in to tend to the sick.

But Dr Alexander had not come on a healing mission, quite the opposite.

It was exactly 75 years ago, May 1945, and he was there to tear the scab off a Nazi cover-up

and expose some of the worst atrocities of World War II.

Horrific medical experiments on concentration camp prisoners.

Up to that point, the Allies had heard rumors about such research, but no one could confirm anything.

That task fell to Alexander, a chubby, balding, bespectacled Army psychiatrist

who'd been expelled from Nazi Germany years before. For unknown reasons, the Army gave Alexander just six weeks to investigate the atrocities,

from mid-May through the end of June.

And in many ways, it was a no-win assignment.

If he failed in his mission, unprecedented crimes might remain hidden forever.

If he succeeded, well, it was almost worse.

Because then he and the rest of the world would have to live with the knowledge of the cruelties

that one human being can visit upon another.

Either way, as his plane passed Dachau and descended toward Munich,

Alexander knew that the proof he needed to expose the Nazis was somewhere on the ground below. Hi, I'm Sam Keene, and you're listening to the disappearing spoon, a topsy-turvy scienceyy History Podcast, where footnotes become the real story. Alexander opened his investigation into the atrocities by interviewing Nazi scientists near Munich about hypothermia. During the war, Germany had lost thousands of pilots and sailors in the cold seas of the North Atlantic.

So researchers had reportedly been submerging inmates at Dachau in ice water and chilling them nearly to death.

The goal was both to study hypothermia and to test new methods of reviving people.

But when Alexander tried to pin the scientists down, they proved evasive.

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