The Betrayal of Anne Frank: A Cold Case Investigation

Rosemary Sullivan, a Canadian biographer, arrives in Amsterdam in May 2019 to document a cold case investigation into one of the most enduring mysteries of World War II: who betrayed Anne Frank and seven others hiding in a secret Annex at Prinsengracht 263 on August 4, 1944. The investigation, launched in 2016 by Dutch filmmaker Thijs Bayens and journalist Pieter van Twisk, grew into a five-year effort involving more than 20 researchers, historians, and investigators, led by Vince Pankoke, a retired special agent of the Federal Bureau of Investigation (FBI).

Sullivan opens with essential background. Otto Frank, born in Frankfurt in 1889, fled Germany with his wife, Edith, and daughters, Margot and Anne, after Hitler's rise to power in 1933. He established a pectin business called Opekta in Amsterdam. After Germany invaded the Netherlands in May 1940, restrictions on Jews escalated rapidly: mandatory registration, confiscation of businesses, and mass deportations. The Netherlands' wartime record was the worst in Western Europe; of 140,000 Jews living there, 107,000 were deported and only 5,200 returned. Otto tried to emigrate, applying for US visas and exploring refuge in Switzerland and England, but bureaucratic obstacles and wartime closures blocked every route.

On July 5, 1942, 16-year-old Margot received a summons for forced labor in Germany. Otto activated a plan he had been preparing for months. The family walked through the rain to the four-story Annex behind his business, where they hid for over two years alongside the Van Pels family (Hermann, Auguste, and their son Peter) and a dentist named Fritz Pfeffer. Four employees sustained them: Johannes Kleiman, Victor Kugler, Miep Gies, and Bep Voskuijl. These helpers risked their lives daily, obtaining food on the black market, forging ration cards, and maintaining the fiction that the rear annex was unoccupied. Bep's father, Johannes Voskuijl, built the bookcase that concealed the entrance.

Anne chronicled their claustrophobic existence in her diary, writing to an imaginary friend named "Kitty." By mid-1944, with the Allied invasion of Normandy underway, the hiders dared to believe liberation was near.

On August 4, 1944, a phone call reached Lieutenant Julius Dettmann at the headquarters of the Sicherheitsdienst (SD), the intelligence arm of the Schutzstaffel (SS). The caller reported Jews hiding at Prinsengracht 263. Dettmann dispatched Sergeant Karl Silberbauer and several Dutch policemen. They found the bookcase, forced it open, and arrested all eight occupants. Silberbauer seized Otto's briefcase, dumping Anne's diary on the floor, an act of greed that inadvertently saved it. The prisoners were sent to Camp Westerbork, a transit camp in the north, and then on September 3 to Auschwitz on the last transport to leave Westerbork.

Of the eight, only Otto survived. Edith died of starvation at Auschwitz. Anne and Margot perished of typhus at Bergen-Belsen. Hermann van Pels died at Auschwitz; Auguste died during transport; Peter died at Mauthausen. Pfeffer died at Neuengamme. Otto was liberated by Russian soldiers in January 1945 and returned to Amsterdam in June, where Miep gave him Anne's recovered diary. Published in 1947, it became one of the most widely read books of the 20th century.

Sullivan traces the cold case investigation in detail. Pankoke combined FBI methodology with historical research. The team searched 29 archives across multiple countries, developed an artificial intelligence (AI) program with Microsoft to process millions of data points, and employed forensic analysis and crowdsourcing. At the US National Archives, Pankoke discovered nearly 1,000 Kopgeld (head-bounty) receipts, proof of the system through which the Nazis paid police and informants for capturing Jews. The team catalogued roughly 30 theories about the betrayal and gradually narrowed the field.

Early suspects included Job Jansen, a former employee who denounced Otto to the Nazis in 1941, and Tonny Ahlers, the man who intercepted Jansen's denunciation letter. Both had ties to the Nationaal-Socialistische Beweging (NSB), the Dutch Nazi party, but neither could reach Dettmann directly, and no evidence placed either in a position to know about the Annex. Warehouse manager Willem van Maaren, the only person officially investigated in two prior police inquiries (1947-48 and 1963-64), was suspiciously inquisitive, but neither investigation found proof of his guilt. The team also investigated Bep's sister Nelly Voskuijl, a Nazi sympathizer, and Ans van Dijk, a Jewish woman coerced into becoming one of the most prolific informants in the Netherlands. Both were eliminated: Nelly lacked proof of involvement, and AI analysis confirmed van Dijk was in the town of Zeist, not Amsterdam, in August 1944.

The breakthrough came when Pankoke reexamined an anonymous note mentioned in Detective Arend van Helden's 1963-64 investigation. Otto said he received the note shortly after liberation. It identified "A. van den Bergh" as the person who reported the hiding place to the Jüdische Auswanderung, the Nazi office overseeing Jewish deportation, and stated that Van den Bergh had submitted "a whole list of addresses" (224). Arnold van den Bergh was a prominent Amsterdam notary and member of the Jewish Council, the administrative body the Nazis created to manage the Jewish community.

The team located a copy of the note among papers kept by Van Helden's son. Typeface expert Bernhard Haas confirmed "with the highest forensic certainty" (243) that the note was typed on Otto's own typewriter before 1957. This was physical evidence Otto had taken seriously enough to copy and preserve.

Investigating Van den Bergh, the team found a man who employed multiple strategies to protect his family: obtaining Sperres (temporary exemptions from deportation), securing Calmeyer status (a reclassification as non-Jewish), and cultivating connections with powerful figures including Alois Miedl, a German art dealer linked to Hermann Göring. By mid-1944, each protection was failing. Van den Bergh's Calmeyer status was under challenge, and Miedl fled to Spain. The team found evidence that the Jewish Council's Contact Committee had access to lists of hiding addresses, compiled through uncensored mail smuggled between Westerbork and Amsterdam. Van den Bergh, through his council position and connections, could have obtained such a list.

Neither Van den Bergh nor his immediate family were ever deported or interned, a highly unusual outcome for Amsterdam Jews. His granddaughter acknowledged that if her grandfather gave up addresses, it was "because he was forced, because he had to save his family's lives" (259).

The Van den Bergh theory is the only one that accounts for Otto's behavior across the decades. He investigated Van den Bergh after returning from Auschwitz but never revealed the name publicly. In her public appearances, Miep used a pseudonym for Silberbauer at Otto's request, possibly to prevent the officer from being traced and revealing Van den Bergh as the source of the tip. In a 1994 lecture, Miep disclosed that the betrayer had died before 1960; Van den Bergh died in 1950. Otto told a journalist the family had been "betrayed by Jews" (274) and told his nephew Buddy Elias he chose not to pursue the betrayer because "it would only take another father away from their children" (200). Van den Bergh had three daughters who survived the war.

Sullivan concludes that Van den Bergh was "a person put into a devil's dilemma by circumstances for which he was not to blame" (288). If he turned over addresses, it was to save his family, not out of wickedness. The ultimate responsibility rests with the Nazi occupiers who "terrorized and decimated a society, turning neighbor against neighbor" (288). After publication in January 2022, a group of Dutch historians published a refutation, and the Dutch publisher Ambo Anthos withdrew the book from the Dutch market. In a postscript, the team defends its core hypothesis, emphasizing it presented Van den Bergh as the likeliest scenario rather than a definitive conclusion, portraying him as another victim of the Nazis rather than a perpetrator.