Anne Frank. Photo: Collectie Anne Frank Stichting Amsterdam.

A new book based on an investigation by a team led by a former FBI agent has concluded that Holocaust diarist Anne Frank’s family may have been betrayed to the Nazis by a Jewish notary who collaborated with the German occupiers.

Anne and her family hid from the Nazis during most of the war, but were captured in August 1944 after being betrayed by a still-unknown informant. They were sent to several concentration camps, and Anne died in Bergen-Belsen shortly before it was liberated by the Allies. Her diary, published after the war, became a classic of Holocaust literature.

Arnold van den Bergh has been named as the prime suspect by the investigators, whose search for the informant is the subject of the new book “The Betrayal of Anne Frank.”

Van den Bergh was a member on the “Jewish council” set up by the Germans when they occupied the Netherlands. He initially attempted to be listed as a non-Jew but was unable to do so.

He reportedly was involved in the looting of Jewish-owned works of art and their transfer to Nazi officials. Van den Bergh is believed to have done this to save his family, who were not sent to concentration camps.

Rosemary Sullivan, author of the book, noted that Van den Bergh initially “was working with a committee to help Jewish refugees, and before the war as they were fleeing Germany,” but later became a collaborator.

“What had happened was Van den Bergh was able to get a number of addresses of Jews in hiding,” she said, as quoted by The Guardian. “And it was those addresses with no names attached and no guarantee that the Jews were still hiding at those addresses. That’s what he gave over to save his skin, if you want, but to save himself and his family.”

“Personally, I think he is a tragic figure,” she added.

The “smoking gun” uncovered by the researchers was an anonymous note pointing to Van den Bergh sent to Otto Frank, Anne’s father, who survived the camps and returned to the Netherlands, where he edited and eventually published his daughter’s diary.

Otto Frank is believed to have been fairly certain that someone in the Jewish community had betrayed the family, but never named names.