Berlin’s ruins still smoldered as three Soviet military intelligence officers questioned a tall, lithe blonde in 1945. A Red Army lieutenant, the group’s translator, opened the burgundy satin cover of a cheap jewelry box and showed her its contents. Nestled inside were charred human teeth, gold dental crowns and a complete lower jaw. “I took the dental bridge in my hand,” Käthe Heusermann wrote decades later. “I looked for an unmistakable sign. I found it immediately, took a deep breath and blurted out, ‘These are the teeth of Adolf Hitler.’ I was showered with expressions of gratitude.” Within weeks, Heusermann...