Despite controversy surrounding its findings, the work of a ‘cold case team’ powerfully illuminates what it was like to live under a genocidal regime

On 4 August 1944 Gestapo officer Karl Josef Silberbauer, together with three Dutch policemen, marched into a spice merchant’s on Amsterdam’s Prinsengracht and demanded: “Where are the Jews?” It was a piercing moment in 20th-century history, one that never becomes dulled by retelling. Within minutes Silberbauer and his accomplices had located a dummy bookshelf, behind which lay a secret suite of rooms where two families had been hiding for two years. Placed under arrest, these eight men and women were subsequently sent to concentration camps in the east from which only one, the business’s owner, Otto Frank, returned.

We know all this because one of Frank’s first postwar acts was to publish the journal that his 15-year-old daughter had kept during their immuration. The Diary of Anne Frank became a canonical text, one of the few accounts we have of living through Hitler’s Final Solution in real time. And it is Anne’s face – peaky, clever, ferociously alive – that has become the emblem of all the evil unleashed by antisemitism in Europe’s terrible mid-century. Yet despite the story being so familiar, there is one detail that remains a mystery. Who tipped off the authorities that there were people hiding at the back of Prinsengracht 263?