On August 4, 1944, police in Nazi-occupied Amsterdam raided a warehouse and arrested eight Jews who were hiding in an annex disguised behind a bookcase. Among those captured was Anne Frank, a 15-year-old schoolgirl who had spent over two years living in the cramped safehouse with her parents and older sister. The diary Frank kept during her confinement is now considered one of the most important accounts of the Holocaust, but the circumstances of her arrest have always been cloaked in mystery. It is believed that an anonymous tip helped guide the Nazis to the secret annex, yet despite decades of investigations, the identity of the informant has never been proven.
Anne Frank’s father Otto—the only member of the family to survive their subsequent deportation to the concentration camps—was among the first to assert that a betrayal had led to their capture. The group’s hideout was located inside a warehouse he had once owned, and they were aided by several of his employees as well as other Dutch sympathizers. Shortly after World War II ended, Otto Frank suggested that the culprit was Willem van Maaren, a warehouse employee who was not in on the secret. Van Maaren was later the subject of multiple investigations related to the betrayal—including one by famed Nazi hunter Simon Wiesenthal—but he always maintained his innocence, and none of the cases ever produced any evidence against him.
In the years since Anne Frank’s diary was published, investigators and historians have proposed several other potential informants. These include Lena Hartog, the wife of one of the warehouse employees; and Nelly Voskuijl, the sister of one of the Franks’ helpers. In 2002, meanwhile, author Carol Ann Lee argued the informant was Tonny Ahlers, a Dutch Nazi sympathizer who had previously been a business associate of Otto Frank. Ahlers’ own son endorsed the theory that his father was the culprit, but a subsequent investigation by Dutch authorities found no hard evidence of his involvement.
The most recent theory surfaced in 2016, when Amsterdam’s Anne Frank House suggested that the group’s arrest could have been a tragic accident. In a research paper, the museum argued that the German Security Service might have simply stumbled upon the eight Jews while raiding the premises to search for fraudulent food-ration cards. Nevertheless, its researchers do not rule out the potential that Frank and the others were the victims of a betrayal. “Clearly,” the museum’s report concludes, “the last word about that fateful summer day in 1944 has not yet been said.”