Anne Frank working on her now-famous diary in Amsterdam, before going into hiding with her family during World War II

Anne Frank Fonds Basel/Getty Images

Who Betrayed Anne Frank?

The German-born teen diarist was captured by the Nazis in 1944 after two years in hiding. Nearly 75 years later, a new investigation aims to solve the mystery of who tipped off the police.

Behind a bookcase that doubled as a secret door, 15-year-old Anne Frank and her family lived in constant fear. If discovered in their hideout—an annex in the back of her father’s business—they could be sent to their deaths.

It was 1944, and throughout Amsterdam, the capital of the Netherlands, the forces of Nazi Germany were rounding up Jews. For the Franks, any wrong move—a loud noise, a window left open, a flash of light—could give them away.

On August 4, the Franks’ worst fears were realized. At around 11 a.m., Dutch police, led by a Nazi officer, forced their way into the annex and dragged everyone away at gunpoint. Soon, all eight people living in the hideout were arrested and sent to concentration camps. Just one of them—Anne’s father, Otto—would survive.

Today, much is known about the Franks’ time in hiding thanks to Anne’s diary, first published in 1947 (see “Through Anne’s Eyes,” below). Yet one aspect of her story has remained a mystery: how authorities found out about the hiding place. Otto, who passed away in 1980, long suspected that one of his employees, Wilhelm van Maaren, had tipped off the police. Yet investigations by Dutch officials in 1948 and 1963 turned up nothing.

Behind a bookcase that doubled as a secret door, 15-year-old Anne Frank and her family lived in constant fear. They hid in an annex in the back of her father’s business. If discovered, they could be sent to their deaths.

It was 1944, and throughout Amsterdam, the capital of the Netherlands, the forces of Nazi Germany were rounding up Jews. For the Franks, any wrong move could give them away. A loud noise, a window left open, or a flash of light could put them at risk.

On August 4, the Franks’ worst fears were realized. At around 11 a.m., Dutch police, led by a Nazi officer, forced their way into the annex. They dragged everyone away at gunpoint. Soon, all eight people living in the hideout were arrested and sent to concentration camps. Just one of them would survive: Anne’s father, Otto.

Today, much is known about the Franks’ time in hiding thanks to Anne’s diary, which was first published in 1947 (see “Through Anne’s Eyes,” below). Yet one aspect of her story has remained a mystery: how authorities found out about the hiding place. Otto passed away in 1980. He had long suspected that one of his employees, Wilhelm van Maaren, had tipped off the police. Yet investigations by Dutch officials in 1948 and 1963 turned up nothing.

The team is using software and artificial intelligence to find the culprit.

Now a new team of detectives, analysts, and historians is determined to crack the case. Using modern technology, including 3-D models of the annex, artificial intelligence, and advanced computer software, they’re hoping to figure out who—if anyone—betrayed the Franks’ whereabouts.      

Vince Pankoke, the former FBI agent in charge of the investigation, says his goal isn’t to punish those involved (most of the suspects are now dead), but to finally solve the case and call attention to the atrocities of the Holocaust. The team hopes to reveal its findings on August 4, 2019, exactly 75 years after the raid on the annex. “This is one of the greatest historical mysteries,” says Deborah Lipstadt, a historian at Emory University in Atlanta. “Anne’s story continues to touch so many people. We all want to find out what happened.”

Now a new team of detectives, analysts, and historians is determined to crack the case. They’re using modern technology to do so. That includes 3-D models of the annex, artificial intelligence, and advanced computer software. The team is hoping to figure out who, if anyone, betrayed the Franks’ whereabouts.

Vince Pankoke, a former FBI agent, is in charge of the investigation. He says his goal isn’t to punish those involved (most of the suspects are now dead). Instead, he aims to finally solve the case and call attention to the atrocities of the Holocaust. The team hopes to reveal its findings on August 4, 2019. That date would mark exactly 75 years since the raid on the annex. 

“This is one of the greatest historical mysteries,” says Deborah Lipstadt, a historian at Emory University in Atlanta. “Anne’s story continues to touch so many people. We all want to find out what happened.”

Jim McMahon

Hitler’s Rise to Power

Anne was 3 years old when Adolf Hitler became chancellor of Germany in 1933. At the time, the country was in desperate shape. Its defeat in World War I (1914-18) and the economic crisis that followed had left the nation humiliated and impoverished.

Hitler gave Germans a scapegoat for all the country’s problems: Jews. He blamed them not only for Germany’s loss in the war but also for the nation’s high unemployment rate and other issues. Once in power, he took advantage of widespread anti-Semitism to systematically target the Jewish people, stripping them of their rights, forbidding them to work in certain jobs, and organizing a boycott of Jewish businesses.

Before long, thousands of German Jews, including the Franks, fled the country in a desperate attempt to escape the Nazis. In 1934, Anne and her family settled in Amsterdam, where they thought they would be safe. And at first, they were. But in 1940, less than a year after Hitler’s invasion of Poland sparked World War II (1939-45), German forces occupied the Netherlands. The conflict eventually engulfed much of the world, pitting the Allies (led by the United States, the United Kingdom, and the Soviet Union) against the Axis Powers (led by Germany, Italy, and Japan). 

As Hitler’s empire grew, hundreds of thousands of European Jews tried to flee to other countries, fearful that they would be deported to concentration camps. But many of them had nowhere to go. Several nations, including the U.S., had set quotas that limited the number of refugees they would accept. Anne and her family were trapped.

Anne was 3 years old when Adolf Hitler became chancellor of Germany in 1933. At the time, the country was in desperate shape. Its defeat in World War I (1914-18) and the economic crisis that followed had left the nation humiliated and very poor.

Hitler gave Germans a scapegoat for all the country’s problems: Jews. He blamed them not only for Germany’s loss in the war but also for the nation’s high unemployment rate and other issues. Once in power, he took advantage of widespread anti-Semitism to systematically target the Jewish people. He stripped them of their rights, forbid them to work in certain jobs, and organized a boycott of Jewish businesses.

Before long, thousands of German Jews fled the country in a desperate attempt to escape the Nazis. That included the Franks. In 1934, Anne and her family settled in Amsterdam, where they thought they would be safe. And at first, they were. But in 1940, German forces occupied the Netherlands. It was less than a year after Hitler’s invasion of Poland sparked World War II (1939-45). The conflict eventually engulfed much of the world. It pit the Allies (led by the United States, the United Kingdom, and the Soviet Union) against the Axis Powers (led by Germany, Italy, and Japan).

As Hitler’s empire grew, hundreds of thousands of European Jews tried to flee to other countries. They feared that they would be deported to concentration camps. But many of them had nowhere to go. Several nations, including the U.S., had set quotas that limited the number of refugees they would accept. Anne and her family were trapped.

Life in Hiding

In 1942, Otto decided that his family had no choice but to go into hiding. His business, which sold pectin, an ingredient in jam, was made up of offices and a warehouse. Behind them was a small building, called an annex, that could be reached only from the inside.

Soon after the Franks moved in, they were joined by Otto’s business partner, Hermann van Pels; van Pels’s wife, Auguste; and their 15-year-old son, Peter. Another Jewish man, Fritz Pfeffer, arrived a few months later. Several of Otto’s employees agreed to help them, risking their lives to provide food and other necessities.

Despite the constant danger, Anne tried to remain optimistic. “It’s difficult in times like these: ideals, dreams, and cherished hopes rise within us, only to be crushed by grim reality,” she wrote in her diary on July 15, 1944, less than three weeks before the raid on the annex. “It’s a wonder I haven’t abandoned all my ideals, they seem so absurd and impractical. Yet I cling to them because I still believe, in spite of everything, that people are truly good at heart.”

In 1942, Otto decided that his family had no choice but to go into hiding. His business, which sold pectin, an ingredient in jam, was made up of offices and a warehouse. Behind them was a small building, called an annex. It could be reached only from the inside.

Soon after the Franks moved in, they were joined by Otto’s business partner, Hermann van Pels; van Pels’s wife, Auguste; and their 15-year-old son, Peter. Another Jewish man, Fritz Pfeffer, arrived a few months later. Several of Otto’s employees agreed to help them. They risked their lives to provide food and other necessities.

Despite the constant danger, Anne tried to remain optimistic. “It’s difficult in times like these: ideals, dreams, and cherished hopes rise within us, only to be crushed by grim reality,” she wrote in her diary on July 15, 1944. That was less than three weeks before the raid on the annex. “It’s a wonder I haven’t abandoned all my ideals, they seem so absurd and impractical. Yet I cling to them because I still believe, in spite of everything, that people are truly good at heart.”

Photo12/UIG via Getty Images (Bookcase); Anne Frank House/Allard Bovenberg, Amsterdam (Room)

After their arrest, Anne and the others in the annex were sent to Auschwitz, in Poland, the most notorious of all the concentration camps. Anne and her older sister, Margot, were eventually transferred to Bergen-Belsen, a concentration camp in Germany, where they are believed to have died of typhus in February 1945, just weeks before the camp was liberated by British troops.

By the time Germany surrendered in May 1945, the Nazis had killed more than 6 million European Jews—two-thirds of the continent’s Jewish population—and 5 million others, including Poles, Roma, Communists, and the disabled. Many had been shot and thrown into mass graves or herded into gas chambers, their bodies then burned in crematoriums. Others died in the camps of starvation or disease. About 1 million of the victims were children.

Today, nearly 75 years after her death, Anne’s story continues to captivate the world. A few years ago, it caught the attention of Pankoke, who was shocked to learn that the circumstances surrounding the Franks’ arrest remained a mystery.

After their arrest, Anne and the others in the annex were sent to Auschwitz, in Poland. It was the most notorious of all the concentration camps. Anne and her older sister, Margot, were eventually transferred to Bergen-Belsen. That concentration camp was in Germany. They are believed to have died of typhus at the camp in February 1945, just weeks before British troops liberated it.

By the time Germany surrendered in May 1945, the Nazis had killed more than 6 million European Jews. That was two-thirds of the continent’s Jewish population. The Nazis also killed 5 million others, including Poles, Roma, Communists, and the disabled. Many had been shot and thrown into mass graves or herded into gas chambers, their bodies then burned in crematoriums. Others died in the camps of starvation or disease. About 1 million of the victims were children.

Today, nearly 75 years after her death, Anne’s story continues to captivate the world. A few years ago, it caught the attention of Pankoke. He was shocked to learn that the circumstances surrounding the Franks’ arrest remained a mystery.

Potential Suspects

Over the years, potential suspects have included Van Maaren; a prominent Dutch Nazi named Tonny Ahlers; and a woman whose husband worked for Otto, Lena Hartog-van Bladeren.

Pankoke says his team has started analyzing millions of pages of scanned documents, including police reports, witness statements, and lists of Nazi informants, and begun to follow up on leads. Previous investigations had to analyze such documents by hand, but new computer software can process the same information in a fraction of the time.

The team also plans to construct a 3-D version of the annex and use computer models to figure out how far sounds could have traveled. They’re hoping to determine whether a neighbor or passerby could have heard the Franks and alerted the authorities.

The investigators have also set up a tip line so people can submit information. They’ve already received hundreds of tips, including from family members of past suspects and people who lived near the annex.

Over the years, potential suspects have included Van Maaren; a prominent Dutch Nazi named Tonny Ahlers; and a woman whose husband worked for Otto, Lena Hartog-van Bladeren.

Pankoke says his team has started analyzing millions of pages of scanned documents. That includes police reports, witness statements, and lists of Nazi informants. The team has begun to follow up on leads. Previous investigations had to analyze such documents by hand. But new computer software can process the same information in a fraction of the time.

The team also plans to construct a 3-D version of the annex and use computer models to figure out how far sounds could have traveled. They’re hoping to determine whether a neighbor or passerby could have heard the Franks and alerted the authorities.

The investigators have also set up a tip line so people can submit information. They’ve already received hundreds of tips. That includes info from family members of past suspects and people who lived near the annex.

‘We owe it to the victims. We’re going to try to solve this.’  

Pankoke says he’s open to all possibilities, including that the Franks were discovered by chance, as some historians have speculated. A 2016 report by the Anne Frank House, a museum created from the Franks’ hiding place in Amsterdam, suggested that the authorities may have gone to Otto’s business to investigate forged food-ration cards and other illegal activities, not to find Jews.

Whatever the investigation turns up, Pankoke says it’s important to call attention to what happened to Anne—and the millions of other Jews murdered by the Nazis.

“We owe it to the victims,” he says. “It doesn’t matter how long it takes, we’re going to try to solve this.”

Pankoke says he’s open to all possibilities. That includes the theory that the Franks were discovered by chance. Some historians have speculated that this was the case. A 2016 report by the Anne Frank House, a museum created from the Franks’ hiding place in Amsterdam, suggested that the authorities may have gone to Otto’s business to investigate forged food-ration cards and other illegal activities, not to find Jews.

Whatever the investigation turns up, Pankoke says it’s important to call attention to what happened to Anne—and the millions of other Jews murdered by the Nazis.

“We owe it to the victims,” he says. “It doesn’t matter how long it takes, we’re going to try to solve this.”

Through Anne’s Eyes

An entry in Anne Frank’s diary, June 6, 1944

Anne Frank Fonds - Basel via Getty Images

Anne Frank’s diary (above), which she nicknamed Kitty, was first published in 1947, two years after her death. It has since been translated into nearly 70 languages and remains one of the most widely read books in the world. The excerpt below was written on D-Day, the day the Allies landed on the beaches of France to begin the liberation of Europe from the Nazis.

A huge commotion in the Annex! Is this really the beginning of the long-awaited liberation? The liberation we’ve all talked so much about, which still seems too good, too much of a fairy tale ever to come true? Will this year, 1944, bring us victory? We don’t know yet. But where there’s hope, there’s life. It fills us with fresh courage and makes us strong again. We’ll need to be brave to endure the many fears and hardships and the suffering yet to come. It’s now a matter of remaining calm and steadfast, of gritting our teeth and keeping a stiff upper lip! France, Russia, Italy, and even Germany, can cry out in agony, but we don’t yet have that right!

Oh, Kitty, the best part about the invasion is that I have the feeling that friends are on the way. Those terrible Germans have oppressed and threatened us for so long that the thought of friends and salvation means everything to us! Now it’s not just the Jews, but Holland and all of occupied Europe. Maybe, Margot says, I can even go back to school in October or September.

Anne Frank’s diary (above), which she nicknamed Kitty, was first published in 1947, two years after her death. It has since been translated into nearly 70 languages and remains one of the most widely read books in the world. The excerpt below was written on D-Day, the day the Allies landed on the beaches of France to begin the liberation of Europe from the Nazis.

A huge commotion in the Annex! Is this really the beginning of the long-awaited liberation? The liberation we’ve all talked so much about, which still seems too good, too much of a fairy tale ever to come true? Will this year, 1944, bring us victory? We don’t know yet. But where there’s hope, there’s life. It fills us with fresh courage and makes us strong again. We’ll need to be brave to endure the many fears and hardships and the suffering yet to come. It’s now a matter of remaining calm and steadfast, of gritting our teeth and keeping a stiff upper lip! France, Russia, Italy, and even Germany, can cry out in agony, but we don’t yet have that right!

Oh, Kitty, the best part about the invasion is that I have the feeling that friends are on the way. Those terrible Germans have oppressed and threatened us for so long that the thought of friends and salvation means everything to us! Now it’s not just the Jews, but Holland and all of occupied Europe. Maybe, Margot says, I can even go back to school in October or September.

Timeline: The Holocaust

Bettmann/Getty Images

1933: Hitler’s Rule Begins

After the Nazi Party wins elections, its leader Adolf Hitler becomes chancellor (similar to president) of Germany. The Nazis burn books by Jews, fire Jews from government jobs, and organize a boycott of Jewish businesses.

After the Nazi Party wins elections, its leader Adolf Hitler becomes chancellor (similar to president) of Germany. The Nazis burn books by Jews, fire Jews from government jobs, and organize a boycott of Jewish businesses.

1935: The Nuremberg Laws

The Nazi Party begins passing laws that strip German Jews and other “non-Aryans” of their citizenship. Jews are banned from schools, hospitals, and other public places.

The Nazi Party begins passing laws that strip German Jews and other “non-Aryans” of their citizenship. Jews are banned from schools, hospitals, and other public places.

Hulton Archive/Getty Images

Smashed windows at a Jewish shop in Berlin, Germany, following Kristallnacht, which means “Night of Broken Glass”

1938: Kristallnacht

On November 9, the Nazis unleash a wave of anti-Jewish attacks, burning and looting synagogues and Jewish-owned shops. They arrest 30,000 Jewish men and send them to concentration camps.

On November 9, the Nazis unleash a wave of anti-Jewish attacks, burning and looting synagogues and Jewish-owned shops. They arrest 30,000 Jewish men and send them to concentration camps.