The tale of Anne Frank’s years spent hiding with her family in the secret annex above her father’s warehouse is known around the world. Yet despite years of research by Otto Frank (Anne's father and the only member of her family to survive the Holocaust) and scholars, we still don’t know exactly what circumstances led to Anne and her family’s discovery. A new investigation is reopening the cold case in the hopes of finally finding out the truth, The Guardian reports.

The long-accepted theory of the Franks’ discovery and subsequent arrest is that an anonymous tip to the Sicherheitsdienst, the Nazi intelligence agency, gave their hiding place away. The 30 potential suspects identified over the years have included a warehouse worker, a housekeeper, and a man possibly blackmailing Otto Frank. In December 2016, researchers at the Anne Frank House floated a new theory: The discovery was incidental, the result of a police raid looking for proof of ration fraud at Otto Frank’s factory, in which police just happened to uncover two Jewish families living in secret. However, none of these theories has been proven definitively.

Now, a team of investigators led by a former FBI agent is taking on the cold case, reviewing the archives of the Anne Frank House in Amsterdam, examining newly declassified material in the U.S. National Archives, and using data analysis to find a conclusive answer to the decades-old mystery.

“This investigation is different from all previous attempts to find the truth,” according to the Cold Case Diary website. “It will be conducted using modern law enforcement investigative techniques. The research team is multidisciplinary, using methods of cold case detectives, historians, but also psychologists, profilers, data analysts, forensic scientists and criminologists.” Thijs Bayens and Pieter Van Twisk, a Dutch filmmaker and journalist, respectively, came up with the idea for the project, and recruited the lead investigator, retired FBI agent Vince Pankoke. Pankoke has previously worked on cases involving Colombian drug cartels.

The new Anne Frank case will focus on investigative techniques that have only become available in the last decade, like big data analysis. Already, the investigators have uncovered new information, such as a German list of informants and the names of Jews that had been arrested and betrayed in Amsterdam during the war, found in the U.S. National Archives.

The investigators hope to provide answers in time for the 75th anniversary of the Frank family’s arrest in August 2019.

[h/t The Guardian]