It was April 28, 1945, and the war in Europe was in its final hours. Days earlier, Martin Dannenberg, an Army intelligence officer, had seen piles of dead bodies at Dachau, the concentration camp in Germany. He said they were stacked like cordwood.

Now he was in a bank vault, opening an envelope sealed with red swastika embossments. He pulled out a document  four typed, black-bordered pages  signed by Adolf Hitler and three top lieutenants. It proclaimed the Nuremberg Laws.

These laws stripped Jews of their German citizenship; forbade marriage and sex between citizens of “German blood” and Jews; and established the swastika as the German flag while forbidding Jews to display it. Announced at a rally in Nuremberg in September 1935 and quickly rubber-stamped by the German Parliament, they provided the legal pretext for the dehumanizing of Jews that led ineluctably to the piles of bodies Mr. Dannenberg saw.

“I had the most peculiar feeling when I had this in my hand, that I should be the one who should uncover this,” Mr. Dannenberg said in an interview with The Baltimore Sun in 1999. “Because here is this thing that begins the persecution of the Jews. And a Jewish person has found it.”