Since the publication of her diary, speculation has been rife about who betrayed Anne Frank and the others hiding in the secret annexe in Amsterdam. Several suspects have been named and, although no one has been proved to be the culprit, one individual is certainly of interest.

Tonny Ahlers, was born Anton Christian Ahlers on December 1917 in Amsterdam. He had a difficult childhood and by the time he was a teenager was known to the Amsterdam police as something of a troublemaker. In 1938 he attempted to drown himself, although it is not known if this was a genuine suicide attempt or merely a means to draw attention to himself as he was reputed to be an excellent swimmer. Some months after this incident he started following the Dutch National Socialist E.H. ridder van Rappard. At the end of 1938 Ahlers took part in the attack on the Bijenkorf Department Store in Amsterdam. Owned by Jews, the mob attacked shop workers and customers before the police arrived. In the following year Ahlers was arrested after smashing the window of the Comité voor Joodsche Vluchtelingen (Jewish Refugee Committee) on Lijnbaansgracht. He was jailed for several months.

When Germany invaded the Netherlands in 1940, Ahlers joined the private police force of the Fokker aircraft company. During his time with the police force Ahlers tracked down Jews in hiding and reported on them to the authorities. While this work may have been done because of political conviction it could equally have been done for financial gain. During the German occupation of Amsterdam, the authorities paid up to forty Guilders per head for every Jew discovered. In the spring of 1941, he visited Otto Frank and showed him a letter written by J.M. Jansen, who had been fired from Frank’s firm Opekta. According to the letter, Frank had stated that ‘The war will not be over soon and Germany will suffer terribly’. Had the letter been delivered to the authorities, Frank would undoubtedly have been arrested. When Ahlers handed over the letter, Frank paid him. Ahlers returned to see Frank a few weeks later and more money was handed over. On his return from Auschwitz Frank discovered that Ahlers was in custody. He wrote to the authorities explaining that Ahlers had helped him over the letter incident in 1941.
However, except for this contact in 1941 there is no evidence of any further connection between Ahlers and Otto Frank. So why should Ahlers be thought of as the one who betrayed the group in the secret annexe? Quite simply because Tonny Ahlers claimed he did.

Ahlers was arrested and convicted for his collaboration with the Nazis in 1946. In June 1947, Otto Frank published the first edition of Anne’s diary and in early 1948, Ahlers was released from prison. Shortly afterwards, Ahlers started to claim he had been the one to discover the group in the annexe. Ahlers stated that he had personally told Maarten Kuiper about the group in the annexe. Kuiper who was a policeman, a member of the National Socialist Movement in the Netherlands (NSB) and the Schutzstaffel (SS), worked for the Sicherheitsdienst (SD) hunting down Jews. He was known for his cruelty during interrogations and always liked to be present at arrests. He was present at the arrest of the group in the annexe. However, while Ahlers convinced his brother and later his son that he was ‘the one’ there is no evidence that he was involved in any way. While it is not impossible for him to have been the person who there are several other suspects much more likely including some of the staff in the warehouse, for example the stockroom manager Willem van Maare. In addition, in the records of Maarten Kuiper, there are a few notes of information about Jews in hiding received from Ahlers, however none of which relate to the secret annexe on Prinsengracht. Before and during the war, Ahlers had lived a somewhat hand to mouth existence. By the time he had been released from prison in 1948, he was over thirty years old, with a record as a Nazi collaborator and with no income. However, for all there was immense interest in who had betrayed the group in the annexe, few, if any, believed Ahlers’ claims. As Anne’s fame spread and the story of the group in the annexe became more widely known, Ahlers continued to claim his role in their capture. This claim was joined by others including the grand import business he had owned just before the war, his inflated role in the SD and the number of Jews he had found. Ahlers cut a rather pathetic figure round the bars of Amsterdam clinging to his claims about Anne Frank. This then backfired on Ahlers. For the few who believed him, his role in sending eight Jews to the camps, of whom seven died, caused revulsion. For the majority, who disbelieved him, there was abhorrence for a man who would make such a claim.

Tonny Ahlers died in the year 2000. The identity of the person who betrayed the group in the secret annexe remains unknown.