For more than 75 years, the diary of Anne Frank has remained one of the most widely read books in the world. Its account of a Jewish teenager's life in hiding gave a voice and a face to millions of victims of the Nazi genocide.
Yet one question has gone stubbornly unanswered: who alerted the Nazi search team in 1944 to Anne Frank and her family's hiding place? Two Dutch police inquiries and countless historians produced theories but no firm conclusions.
Then, in 2016, a team of investigators led by a veteran FBI agent decided to bring modern crime-solving techniques and technology to this cold case. They now believe they have an answer.
Vince Pankoke had turned in his badge and gun and was two years into a comfortable Florida retirement when his phone rang in the spring of 2016. A colleague from the Netherlands asked if he was done lying on the beach and told him they had a case.
Pankoke spent three decades as an FBI special agent targeting Colombian drug cartels. His work had also taken him to the Netherlands, where his investigative skills left an impression.
When he heard the case involved trying to solve the mystery of what caused the raid on Anne Frank and the others in the annex, he needed to hear more.
Four thousand miles away in Amsterdam, Dutch filmmaker and documentarian Thijs Bayens had been asking around for a credentialed investigator to dig into a question he felt Holland had never quite reckoned with—one that gets to the essence of human nature.
For Bayens, it was important to investigate what makes people give up on each other. The area where Anne Frank lived was very normal and warm, with the butcher, the doctor and the policemen working together and living together. Suddenly, people started betraying one another.
Asked why this story resonates among the millions to come out of the Holocaust, Bayens said that right after the war people were shown the concentration camps and the atrocities. Then they found this innocent, beautiful, smart, funny and talented girl who emerged like a lighthouse from the darkness, and humanity said: this is who we are.
Betraying fellow Dutch to the Nazis was a criminal offense in the Netherlands, but two police probes and a whole library of books yielded neither convictions nor definitive conclusions.
Pankoke's approach was simple: if it is a criminal act, it should be investigated by police. So the team set it up as a cold case.
Pankoke had read the diary in middle school in western Pennsylvania, and it left a mark. There would be no perp walks or busted crime syndicates, but he was intrigued—cautiously. He worried the project might have the ring of a schlocky media creation and did not want to be associated with a tabloid-type investigation.
What sealed it for him was the guarantee of absolute autonomy. Bayens would oversee the operation and could film the process for a documentary, and there would be a book, which helped finance the project along with funding from the city of Amsterdam. But it would be an independent undertaking with serious investigators, and Pankoke would take the lead.
Pankoke had worked cold cases before, but the biggest gap in time he had previously faced was about five years. This was 75 years—more than cold. As he put it, this was frozen.
To chip away, Pankoke drew up his own blueprint. He knew there would be more information to plow through than any human could handle, and that artificial intelligence could be a secret weapon.
An FBI man's dream team was assembled: an investigative psychologist, a war crimes investigator, historians, criminologists and an army of archival researchers. Their disparate skills brought different views and helped the team understand and put into context a crime that happened in 1944.
Together they dove into a familiar story. The Frank family had moved to Amsterdam from Germany to escape the rise of Hitler and found safety in Holland, where Otto Frank ran a manufacturing business. Then the Nazis invaded in 1940.
Two years later, the Franks—Otto, his wife Edith, Anne and her sister Margot—along with four other Jewish friends of the family went into hiding in an annex behind Otto's warehouse. Today it is preserved as a museum.
Historian Gertjan Broek of the Anne Frank House showed the famous bookcase used to camouflage the entrance to the hiding place. The bookcase helped protect the Franks, as did a handful of Otto's close colleagues at the warehouse who were in on the secret.
After the raid, the Nazis took anything that wasn't nailed down. Recreations show what the hiding place looked like: two cramped floors, 761 days—more than two excruciating years indoors.
The office workers brought food and supplies, but the eight in hiding couldn't make a sound during the day. By night they could listen to the radio, desperately plotting updates from the front on a map, with a newspaper clipping from shortly after D-Day in June 1944 and pins to follow the advances of Allied troops. There was hope as Allied forces were on the way.
Their life depended on what would happen. Anne's bedroom walls, familiar to any teenager, were preserved from the day she was taken away. There she chronicled the monotony and horror of life in hiding.
"Outside things are terrible day and night," she wrote in January 1943. "These poor people are being dragged away with nothing but a backpack and a little bit of money." Her last entry was dated August 1, 1944. She was 15.
On the day of the raid in the summer of 1944, it was warm and sunny. Around 10:30 or 11, a couple of men walked in. They were detectives with a Dutch police unit working with the Nazis. An SS officer named Silberbauer led the team.
They demanded to be shown around the warehouse and ended up in front of the bookcase hiding the entrance to the annex. Two of the policemen present had been seasoned detectives, experienced in searching this type of building in the inner city of Amsterdam, and they knew there was likely something behind that bookcase.
The stunned inhabitants they found were marched out. Behind them, Anne's diary was preserved by a quick-thinking office worker loyal to the Franks.
Of the eight taken away, Otto Frank was the only survivor. The others were among the hundred thousand Dutch Jews—three-quarters of the country's Jewish population—to die at the hands of the Nazis.
In an interview with CBS in 1964, Otto recounted what happened when his family was put on the cattle cars to Auschwitz a month after their capture, on September 4, 1944. When they arrived at Auschwitz, men with clubs stood there, separating women and men right at the station. The women went to Birkenau and the men to Auschwitz. He never saw his family again.
After the war, Otto Frank was determined to find out who betrayed the hiding place. It was the question many readers asked after he published his daughter's diary in 1947. But after a couple of years, Otto abruptly stopped looking.
When Pankoke went to Amsterdam to begin his search, his first stop was the scene of the crime—what he calls the most visited crime scene in the world, because millions of people from all over come there.
As an investigator, he wanted to see what was in the area, reconstruct how the arrest took place and who participated. Pankoke and his team spent hours in the annex looking for any clue, however remote. They also cased the exterior, which today is almost exactly as it was then.
The courtyard behind the annex is totally enclosed and surrounded by the buildings of the neighborhood. Pankoke thought about a cough overheard, a window open at the wrong time. The sheer risk factor, he said, was extraordinary.
One early theory was that the raid may have been caused by somebody in the immediate area seeing or hearing something and reporting it. The team tracked and identified every resident who lived in the block and adjacent streets using the artificial intelligence program.
They mapped potential threats in the courtyards surrounding the annex and found Nazi party members and even known informants living just a wall or two away. Looking at those threats, Pankoke said, the question might not be what caused the raid but how they lasted more than two years without being discovered.
The team compiled a list of ways the annex could have been compromised: carelessness by the people occupying it, making too much noise or being seen in the windows, or betrayal. Pankoke rejected the theory that no one betrayed the Frank family and that it was coincidence or good detective work. The team took that theory apart bit by bit.
It had been more than seven decades since Anne Frank and her family were discovered and ultimately put on cattle cars to Auschwitz. All the witnesses were long dead and their evidence thinned by time, but Pankoke leaned on decades of experience and intuition, starting with the old case files.
In a normal cold case, you go to a file, pull it out and read through everything the previous investigation did—interviews, leads that were followed up on. Two previous Dutch police investigations into the raid, one in 1948 and another in 1963, were not exactly master classes in detective work. A lot of time had passed, the files were incomplete and scattered across probably a dozen different archives. Reports were missing, witnesses had passed on and memories had failed.
Following the standard cold case playbook, Pankoke followed up on what leads he could. Otherwise, he and his team had to take a fresh approach. They spent years in places like the Amsterdam city archives, where the meticulous Dutch record keeping used so brutally by the Nazis proved a major asset.
With Peter van Tvsk, a veteran Dutch journalist who co-founded the project and led the research team, they showed a trove of items they dug up, including a residence card belonging to Anne Frank. It showed her name, date of birth and the notation "NI," standing for Netherlands Israëlis, a religion. Every Dutch resident had to have one, and it listed her parents' birth dates—which is also why it was quite easy for the Nazis to find people in the Netherlands and know who was Jewish and who was not.
The team fed every morsel they could—letters, maps, photos, even whole books—into an artificial intelligence database developed specifically for the project. Then they let machine learning do its thing, identifying relationships between people and similar addresses, looking for connections. It saved thousands and thousands of man hours and also helped exclude what was garbage and what wasn't going to help the case.
The team paid particular attention to arrest records from the time the Nazis were hell-bent on ridding the Netherlands of all Jews as part of the Final Solution. By 1942, the Franks were among some 25,000 Jews in hiding across the country.
The Nazis were coldly skilled at getting people to talk. Their typical method was that once they arrested somebody, the first question posed was whether they knew where any other Jews were hiding. The team chronicled all the arrests prior to and just after the annex raid to try to find any connection—any loose thread showing they went from one arrest to another and ultimately to the annex. The implication was that a prisoner's sentence might be made more lenient in exchange for names. It was very effective.
Before long, dozens of suspects emerged. One was Willem van Maaren, an employee in the warehouse where the Franks were hiding, whom the Dutch police had interviewed. He was prime suspect number one after the war—working downstairs in the warehouse, shifty, suspicious, actually a thief.
Yet the team eliminated him. He was not a betrayer and not anti-Semitic, and he had incentive not to betray them: if he did, he would have lost his job because the business would have been closed.
In considering suspects, the team looked at knowledge, motive and opportunity. Did they have the knowledge? What was the motive—were they anti-Semitic, were they trying to do this for money? And were they even in town?
Bram van der Meer, an investigative psychologist who had worked with the national police force in the Netherlands, analyzed the behavior and mindsets of suspects. The first instinct might be that a psychopath had to do this, but he cautioned that it was war and survival. Day-to-day life was filled with fear, and people thought every day about their own survival. In a vacuum it had to be a psychopath, but given the context, it could be anybody.
Over time, the team's focus shifted to someone who on the surface might not have raised suspicions. The suspect wasn't a neighbor of the Franks and didn't work for them, but Pankoke's sixth sense kicked in.
Arnold van den Bergh was a prominent Jewish businessman with a wife and kids in Amsterdam. After the invasion he served on the Jewish Council, a body the Nazis set up nefariously to carry out their policies within the Jewish community. In exchange for doing the Nazis' bidding, members might be spared the gas chambers.
The team knew from history that the Jewish Council was dissolved in late September 1943 and its members were sent to the camps. They figured that if Arnold van den Bergh was in a camp somewhere, he certainly couldn't be privy to information that would lead to the compromise of the annex.
They searched, but couldn't find Arnold van den Bergh or any of his immediate family members in those camps. If he wasn't in the camps, where was he? It turned out he was living in open life in the middle of Amsterdam—possible, Pankoke said, only if van den Bergh had some kind of leverage.
Pankoke described him as a chess player who thought in terms of layers of protection by obtaining different exemptions from being placed into the camps. Van den Bergh, who died in 1950, had come up before in a report from the 1963 investigation, though astonishingly there was little apparent follow-up by police.
The team read one small paragraph mentioning that during the interview of Otto Frank, he told investigators that shortly after liberation he received an anonymous note identifying his betrayer and the address where they were staying—the annex—as Arnold van den Bergh.
Remarkably, the reference to the note mentioning this specific name was listed right there in the files. The note was so striking to Otto Frank that he typed up a copy for his records.
Naturally, the veteran FBI man wanted to know where that note was. Any seasoned investigator will tell you that ideally good shoe leather comes garnished with good luck. In 2018, the team located the son of one of the former investigators. In the son's home, buried in some old files, was Otto's copy of the note.
Pankoke said it didn't feel like a smoking gun, but it felt like a warm gun with the evidence of the bullets sitting nearby. Back at the archives, the team showed Otto's copy and used forensic techniques which they say authenticate it, along with the scribblings of the 1963 detective.
The anonymous note informed Otto that he had been betrayed by Arnold van den Bergh, who had handed the Nazis an entire list of addresses where Jews were hiding. Whoever authored the note knew so much—that lists were turned in—and the team was able to corroborate that information. Peter located records in the national archive indicating that somebody from the Jewish Council, of which Arnold van den Bergh was a member, was turning over lists of addresses where Jews were in hiding.
The team's theory of the case: in his role as a founding member of the Jewish Council, van den Bergh would have had access to addresses where Jews were hiding. When he lost his series of protections exempting him from having to go to the camps, he had to provide something valuable to the Nazis to keep himself and his wife safe at that time.
There is no evidence to indicate that he knew who was hiding at any of the addresses. They were just addresses where Jews were known to have been in hiding.
The team contacted the foundation Otto Frank started in Switzerland and the Anne Frank House in Amsterdam, neither of which formally participated in the investigation, to try to find out whether they could provide any other evidence that might implicate or clear Arnold van den Bergh. The Anne Frank House said they could not. The foundation is reserving comment until it has seen the entire results of the investigation.
The cold case team began to confront the real possibility that Otto Frank might have known the identity of the betrayer. They wondered what reason he would have had to keep it to himself. He knew Arnold van den Bergh was Jewish, and in the period after the war anti-Semitism was still around. Perhaps he felt that bringing it up again, with van den Bergh being Jewish, would only stoke the fires further.
But the team had to keep in mind that the fact that he was Jewish just meant he was placed into an untenable position by the Nazis to do something to save his life.
The team wrestled with these ethical questions. Thijs Bayens, who conceived of the project, wondered whether the revelation would be fodder for bigots and anti-Semites. The conclusion was that this culprit was a Jewish man who by all accounts was doing what he did to protect his own family.
Bayens found it very painful. He said he even hoped it wouldn't be something like this, because he feels the pain of all these people being put in a situation very hard for us to understand. He suspects people around the world will be uncomfortable with the idea that a Jew betrayed another Jew, and he hopes so—because it shows how bizarre the Nazi regime really operated and how it brought people to do these terrible things. The real question, he said, is what would I have done.
Throughout the project, Bayens sought counsel from Menachem Sebbag, an orthodox rabbi in Amsterdam who also serves as chief Jewish chaplain in the Dutch army. Asked whether a greater good is being served, the rabbi said he truly hopes so. He hopes people will understand that one of the things Nazi ideology did during the Holocaust was to dehumanize Jewish people, and that going back into history and looking for the truth is actually giving Jewish people back their own humanity—even if that means Jewish people are sometimes seen as not acting morally correct. That gives them back their humanity, because that is the way human beings are when faced with existential threats.
After his years of investigating this seven-decade-old cold case, Pankoke was asked a hypothetical: back as an FBI agent, with the case built and the evidence handed to a prosecutor, would he get a conviction? He said no—there could be some reasonable doubt. It is a circumstantial case, as many cases are, and today's crime solving wants positive DNA evidence or video surveillance tape, none of which they could provide. But in a historical case this old, with all the evidence they obtained, he thinks it is pretty convincing.
Now back in retirement, Pankoke thinks he has glimpsed a new way to thaw cold cases. He marvels that an investigation that put no one behind bars turned out to be the most significant case of his career—and one he believes brought an answer to a painful historical question.