On 4 August 1944, Nazi SD officers raided the Prinsengracht 263 warehouse in Amsterdam, the Netherlands, and discovered the secret annex where Anne Frank and her family had spent the last 761 days in hiding. After being discovered, the Franks were sent to concentration camps. Only Otto Frank survived.
But why did officers search the building that day? Did someone betray Anne Frank and her family, and if so, who? This question plagued Otto Frank for years after the war, and has puzzled historians, researchers and amateur sleuths alike for decades since.
In 2016, retired FBI agent Vincent Pankoke assembled a team of researchers to reopen the cold case. They concluded that Arnold van den Bergh, a Jewish businessman living in Amsterdam, may have given up the Franks’ whereabouts to protect his family. But the theory isn’t without its critics, and van den Bergh is just one of countless culprits investigated over the years as the person who betrayed the Frank family.
Here’s the story of the raid on the secret annex and the possible suspects behind it.
What happened to the Frank family?
Threatened by the Nazis’ persecution of Jews in Holland and across Europe, the Frank family entered the secret annex of Otto Frank’s former workplace at Prinsengracht 263, Amsterdam, on 6 July 1942. They were later joined by the Van Pels family and Fritz Pfeffer.
The room was only accessible by a single door, hidden by a bookcase, and just four employees knew about the secret annex: Victor Kugler, Johannes Kleiman, Miep Gies, and Bep Voskuijl.
After two years in the annex, police offers – led by SS Hauptscharführer Karl Silberbauer – stormed the building and discovered the secret room. The Frank family were arrested and eventually sent to concentration camps. Anne died, probably of typhoid, between February-April 1945. When the war ended, Otto Frank was the only member of the family alive.
Who are the suspects?
Willem van Maaren
Otto Frank spent years after World War Two trying to discover who had betrayed his family. One of the people he closely suspected was Willem van Maaren, who had been employed at the warehouse where Otto had worked and the Franks had hidden. The four workers who knew about the annex and brought the Franks food expressed their distrust of van Maaren.
Van Maaren wasn’t thought to have known about the hiding place, however, and insisted on his innocence after the war ended. Two subsequent Dutch police investigations into him uncovered no strong evidence of his involvement.
In 1998, author Melissa Muller published Anne Frank: The Biography. In it, she raised the theory that Lena Hartog, who had worked in the warehouse as a maid, could have suspected the hiding place existed and revealed this to the Nazis to protect herself and her family.
In her 2003 book Anne Frank’s Story, author Carol Ann Lee hints at Anton Ahlers, better known as Tonny, as a suspect. Tonny was a former colleague of Otto Frank and also a vehement antisemite and a Dutch National Socialist.
Ahlers is thought to have had links to the Nazi security service and is believed to have confronted Otto Frank (before he went into hiding) about Otto’s distrust of the Nazis.
Some have speculated that Ahlers may have passed on information about the warehouse to the Nazis, but there’s no clear evidence that Ahlers was aware of the secret annex.
Nelly Voskuijl was the sister of Bep Voskuijl, one of the four warehouse workers who knew about and aided the Franks’ concealment. In a 2015 biography of Bep, it was suggested that Nelly may have betrayed the Franks.
Nelly was suspected because of her involvement and association with Nazis over the years: she had worked for the Germans on occasion and had an intimate relationship with an Austrian Nazi. Perhaps she had learned of the secret annex through Bep and revealed its whereabouts to the SS. Again, this theory hinges on speculation rather than firm evidence.
The historian Gertjan Brock, as part of an Anne Frank House museum investigation, reached an entirely different conclusion in 2017. Brock suggested that there may have been no betrayal at all and that in fact the annex may have been uncovered due to the SS raiding the warehouse to investigate illegal wares and trades.
Anna ‘Ans’ van Dijk
In the 2018 book The Backyard of the Secret Annex, Gerard Kremer raised the theory that Ans van Dijk was responsible for the Franks’ capture.
Kremer’s father had been a supporter of the Dutch resistance and an associate of van Dijk. Kremer states in the book that his father once heard van Dijk mention Prinsengracht (where the warehouse and secret annex were) in a Nazi office. Later that week, Kremer writes, the raid took place.
Van Dijk was executed in 1948 for aiding the Nazis in the capture of 145 people. The Anne Frank House conducted its own research into Van Dijk’s involvement, but couldn’t confirm it.
Arnold van den Bergh
In 2016, former FBI investigator Vince Pankoke opened a cold case investigation into the discovery of Anne Frank and her family. Utilising modern forensic techniques and AI tools to analyse the existing evidence, Pankoke and his team discovered a new suspect: Arnold van den Bergh.
Van den Bergh was a Jewish notary who worked for the Jewish Council, an organisation set up by the Nazis to influence the Jewish population of occupied Holland. The cold case team theorised that van den Bergh, given his role in the Jewish Council, had access to a list of addresses thought to be housing Jews. They posit that van den Bergh may have shared the list with the Nazis to secure his own family’s safety.
Pankoke and his team also raise an anonymous note, sent to Otto Frank, as evidence. The typed message, which may have been overlooked by previous researchers, appears to identify van den Bergh as the culprit for the Franks’ betrayal.
But after Pankoke’s theory was made public in Rosemary Sullivan’s 2022 book The Betrayal of Anne Frank: A Cold Case Investigation, several historians and researchers spoke out against it.
According to Bart van der Boom, a historian at Leiden University, the suggestion van den Bergh and the Jewish Council had access to a list of addresses housing Jews is “a very serious accusation” made with “virtually no evidence”.
Van der Boom isn’t alone in his critique of the theory. Johannes Houwink ten Cate of the University of Amsterdam told a Dutch media source that “with great accusations comes great evidence. And there is none.”
Ultimately, it seems that unless any new evidence is uncovered, the truth of how Anne Frank and her family were discovered will remain subject to speculation and debate for many years to come.