Lieutenant Herman Schmidt wasn’t far from where the two guards at the checkpoint were gunned down. Once he was made aware, he mediately demanded to be taken to the scene.

Two dead men were laying where they’d bled out. One had been shot multiple times in the chest, the other right between the eyes. Someone had been very good with a pistol.

“Whose car is this?” he asked an agent of the Gestapo who was investigating the shooting.

“Dr. Gehard Volker. He’s ...