The Betrayal of Anne Frank: A Cold Case Investigation

A few weeks later, on April 18, 1941, a young man paid an unexpected visit to Opekta and asked to see Otto Frank. When he was ushered into Otto’s office, he introduced himself as a courier between the NSB and the German SD and asked Otto if he knew a man named Jansen. Slowly the courier removed a letter from his pocket and handed it to Otto. The letter was addressed to the NSB.

Otto looked at the signature: Job Jansen, Member 29992. The letter was a denunciation of Otto for “publicly insulting the Wehrmacht” and “attempting to influence him.” Jansen requested that the SS be informed and that the Jew Frank be arrested. Otto immediately understood that Jansen was reporting him for his remarks about the German Army during their brief encounter on the Rokin. The very appreciative Otto gave the young man the cash he had in his pocket, a mere 20 guilders, to thank him for intercepting the letter. At the time, he was convinced that the young man had saved his life.2

Otto later told the police that he’d let Miep read the letter and then had given the original to his lawyer for review. After taking a few notes, his lawyer destroyed it, with Otto’s permission, since it was deemed too dangerous to keep.3

After the war and when searching for the person responsible for the raid on the Annex, Otto didn’t forget about his former disloyal employee. It was unusual for Otto to react as he did, but on August 21, 1945, he wrote a scathing letter to the authorities in Amsterdam to inquire if they had Jansen in custody. He claimed that the man had committed treacherous acts against him. He was careful to insist that Jansen’s wife, who was Jewish, had in no way been involved but said she might be able to help them find him if he was not yet in jail.4 Perhaps it was Jansen’s disloyalty that cut Otto so deeply. He’d helped the man and his family by employing them in a time of great economic distress, and the man had betrayed him. Had Jansen’s letter reached the SD on Euterpestraat, Otto would certainly have been arrested and, at the least, been sent to a concentration camp.

Because Otto initially suspected Job Jansen of being responsible for the raid on the Annex, Vince believed it was logical for the Cold Case Team to begin their investigation with him. They were able to locate Eric Bremer, a relative of Jansen’s wife, Jetje, and Vince interviewed him on April 23, 2017, at the Tolhuistuin restaurant in Amsterdam-Noord. Bremer had nothing to say about the betrayal of Otto and the other people in the Annex, but he did claim that there was a rumor in the family that Jansen had been responsible for betraying his own sons to the Nazis.5 Of course, this was critical information for the team. Someone capable of such a betrayal would not hesitate to betray his former Jewish employer, against whom he held a grudge.

In the Jansen CABR file the team found Jetje’s testimony about the arrest of her sons:


In September 1941, at four in the morning, two of his sons were arrested, taken out of their beds, and taken to Overtoom police station by two Dutch police officers. My husband was not present during the arrest, as he was staying at a different address. After the arrest of my two sons, I said to my husband, “What do you think about that? Two of your children have been arrested, and you’re an NSB member.” And to that he replied, “Oh, well, in a war there simply must be casualties.”6



It’s a chilling statement. What kind of father would respond to the arrest of his sons in such a way? Was he hiding his guilt?

The statement is all the more devastating given the fate of Jansen’s sons. One was shot in Neuengamme concentration camp on August 18, 1942, as he walked toward the electrified fence, saying he’d suffered enough. The other endured the horrors of Auschwitz and Dachau, though he did survive the war.

Soon, however, the team found a September 10, 1947, postwar declaration by Jansen’s surviving son, Josephus, in which he stated that he and his brother had been betrayed by a postman who kept a list of all members of their resistance group. (Apparently, the man was on holiday, got drunk, and bragged about the list of names he held.) Josephus claimed that his father had tried to intercede with the Germans to get them released.

That testimony was an interesting early warning for the Cold Case Team’s researchers that nothing could be taken at face value. The bitter words of a wife must be checked against the facts. Even then, the acceptance of one statement over the other involves an interpretation: Did the first statement simply reflect the acrimony between husband and wife? Was the son covering for his father? In the end, what sways is the facts. The postman was found to have betrayed others along with the Jansen sons.

But that still left the team with the question: Was Otto right in suspecting that Jansen reported the people in the Annex to the SS? Vince was beginning to use the law enforcement axiom “motive, knowledge, and opportunity” to examine each case.*

In Jansen’s file, the team found a postwar psychological assessment by Dr. W. Ploegsma, written in 1948 and obviously commissioned by the Amsterdam police, in which Jansen is described as a narcissist who played the victim and wallowed in self-pity. “Grudges, excessive guilt, impulsive behavior, restraint, servitude, excessive sense of dignity, lust for power; one can find all this within him.”7 Jansen was jealous of Otto Frank because Frank was “a man who could earn his own money.” Jansen first joined the NSB in 1934 but had had to withdraw after two years because he could not afford the membership fees. He later rejoined because, as he told the psychologist, “he wanted to show that he was a man.”

This would seem to suggest that Jansen had sufficient motivation to betray those in the Annex. Or it might be simpler: If he betrayed Otto once, why not twice? The real test would rest on whether he had knowledge and opportunity to commit the crime of betraying Jews.

To confirm that Jansen possessed knowledge of Otto’s hiding in the Annex was more difficult and perhaps possible only through making assumptions. Even though Jansen was separated from Jetje during all or part of the time that the Annex was occupied, could it be assumed that he remained in contact with her? Since she was technically still married to a non-Jew, she was exempt from having to emigrate and continued working in her flower shop. Was it possible that she heard about Otto and the others hiding in the Annex and mentioned them to Job? Or was it possible that he or his new NSB-sympathizer girlfriend had a connection to someone who lived in the neighborhood or was supplying food to the helpers? The Cold Case Team came up empty in their efforts to find any information that could conclusively answer these questions.

That left the team to consider whether Jansen had the opportunity to betray the people in the Annex. A deep dive into Jansen’s CABR file revealed that by 1944 he was working for a Dutch theater troupe that performed in German and was living in Winterswijk, near the German border. On August 15, eleven days after the raid on the Annex, he was jailed in the city of Munster, Germany, for theft.8 Had he managed, in the eleven days between the raid and his arrest, to return to Amsterdam, to somehow learn of the Jews hiding in the Annex, betray them, and get back to the other side of the country at a time when travel was very difficult? It seems unlikely but can’t be dismissed entirely, given Jansen’s vendetta against Otto.

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