The cold case investigative experience of a one-time Queensland cop has proven critical in the international effort to pin down who betrayed Anne Frank's Amsterdam hiding place to the Nazis.
The team spent five years combing through evidence in a bid to unravel one of World War II's enduring mysteries, and last month revealed the name of the person they believe was most likely responsible.
The cold case team's findings were outlined in a new book called The Betrayal of Anne Frank: A Cold Case Investigation, by Canadian academic and author Rosemary Sullivan.
Former Queensland homicide detective Brendan Rook came to the Anne Frank team while he was tracking war criminals for the International Criminal Court (ICC) in The Hague.
As a homicide detective in Queensland, Mr Rook had worked on the 1970 Mackay sisters murders investigation and was on the team that arrested serial killer Leonard John Fraser.
"Cold cases require a different skill set given the passage of time – (there are) memory issues, lack of reliable witnesses, understanding how rumour pollutes an investigation, former corrupted investigations, where to start, taking yourself back in time," Mr Rook said.
"What was normal then is not normal now."
'More frozen than cold'
Mr Rook left the Queensland Police Service in 2010 to become a war crimes investigator for the ICC. His role, which concluded last year, included financial and weapons trafficking investigations.
"[The Anne Frank] project appealed to me for a number of reasons. Firstly, at the time I was a war crimes investigator with the International Criminal Court … and the court was established on the back of war crimes committed in World War II. Secondly, I was a former homicide detective having worked on cold cases of which this particular case was more frozen than cold."
Anne Frank is the world's best-known victim of the Holocaust. Her diary detailing the life of the 14-year-old and her family while hiding from Nazis has captivated readers for decades.
For more than two years, the Frank family hid with four other people in the small attic of a canal-side annexe in central Amsterdam above a spices warehouse owned by Anne's father, Otto.
On the morning of August 4, 1944, the annexe was raided by officers of the SS Jew Hunting Unit. Anne's diary was left behind in the raid and later published by her father in 1947.
The Franks were taken on the last train to Auschwitz where Anne, her mother Edith, and sister Margot perished in concentration camps in 1945. Otto Frank was the only member of the family to survive.
After the war, he returned to Amsterdam and spent several years searching for those who betrayed them to the Nazis. He was sent an anonymous note naming the alleged betrayer.
He told a journalist in 1948 he had been betrayed by a fellow Jew, but never named the person publicly or declared the note's existence. In 1963, the note came to the attention of police, but they were focusing on other suspects, including a warehouse employee from the Spice factory.
The investigative team treated Anne Frank House in Amsterdam as their crime scene.
"If there is anything I have learnt or had reinforced in this cold case into Anne Frank, throughout all the confusion, fear, guilt, betrayals imposed by the Nazi-occupied Netherlands, is that time itself does not heal the wounds of the past — it's the truth and only the truth that can set that course," Mr Rook told the ABC.
"I believe this is what Otto Frank was trying to achieve when he finally revealed the secret that he had kept all those years, producing the note of the betrayer to Dutch detective [Arend] van Helden nearly 20 years later.
"After Otto made these revelations, the details of the note remained a secret for the next 55 years until [our] cold case investigation located the original copy of the note in a box in the attic of the late Detective van Helden. It was unknowingly in the possession of van Helden's son."
The note alleged that Dutch Jewish legal notary Arnold van den Bergh was the informant.
Mr Rook said the cold case investigators believe Mr van den Bergh handed over a list of several addresses of hiding places of Jews in Amsterdam to save his family from deportation.
Mr van den Bergh and his family survived the war. He died of throat cancer in 1950.
But Mr Rook said Mr van den Bergh was not someone who immediately jumped out from the original list of 30 suspects.
"The investigation had so many twists and turns that at any given time took us in a certain direction only to then find they were eliminated from the investigation — I was convinced that any one of around 20 suspects on our list could have been the betrayer until they were eliminated.
"The Nazi occupation of the Netherlands created a minefield of reasons why someone would betray another, even if that resulted in a death. Vince and I often discussed scenarios, possibilities, realities, mindsets, motives, in order to generate relevant suspects beyond those already identified."
Mr van den Bergh was a member of the Jewish Council established by the Nazis to govern Jewish communities in German-occupied Europe.
Membership of the council offered special privileges and as part of their role, they provided lists of Jews for deportation, Mr Rook said.
A team member found documents in the Dutch National Archives revealing five entries of the Jewish Council having lists of Jews' addresses.
The investigators suspected that when Mr van den Bergh lost the protections that exempted him from having to go to the camps, he provided the locations of Jews in hiding to the Nazis to keep him and his wife safe. His daughters were already in hiding.
Approached by former FBI agent
Mr Rook joined the Anne Frank cold case team after being approached by Dutch producer Thijs Bayens in 2018.
The head of the team, retired ex-FBI agent Vince Pancoke, had asked Mr Bayens to find an investigator he could work with and bounce ideas off.
"Of note, every investigation into who betrayed the Franks up to this point was suspect driven, not evidence led, meaning the projects commenced with a target in mind and then built the case around that target. What was different here is that Thijs suggested we go where the evidence takes us and see what happens, essentially with no suspect in mind,'' he said.
Mr Rook said his experience in homicide and war crime investigations had familiarised him with managing "mass information" and how to focus on relevant details.
The team included archival researchers, criminologists, historians, and investigative psychologists, and used artificial intelligence to manage the data collected.
They examined information from previous investigations, statements, profiles of people involved in the raid on the Franks, Nazi files, museum files and whether Jews arrested by the Nazis were forced to disclose information about others in hiding.
They also interviewed relatives of the key figures who have since died.
When their theory was finally revealed last month, Mr Rook said the investigation team expected criticism once the book on their investigation named Mr van den Bergh as the likely informant.
"Like with any investigation, and particularly one as high profile as the betrayer of Anne Frank, we anticipated some degree of scepticism,'' he said.
"Ultimately the Nazis are responsible for what happened to the Jewish community. I have come to believe van den Bergh was a victim too."
