Vince was well aware of the monumentality of the undertaking and knew he had to define a strategy for organizing the investigation. The first task was to review and question all of the previous findings, statements, and theories, specifically files from the 1947–48 PRA investigation and those from that of the 1963–64 State Department of Criminal Investigation.
Vince was surprised to find that there wasn’t a central archive where the investigative files were located. Most of the PRA files were found within various CABR files in the Netherlands National Archives, some copies and others originals with no apparent consistency. The State Department of Criminal Investigation files, which were primarily at NIOD, were organized in a more logical fashion. With both investigations, the team was immediately stalled when told by archive officials that they could not have copies of the files due to the recently enacted European General Data Protection Regulation. That was a shock to Vince, who was used to the liberality of US Freedom of Information Act rules. Illogically, the team was permitted to read and hand transcribe the reports, just not to photocopy them. Luckily, many of the research contacts Thijs and Pieter had developed shared the copies they had obtained prior to the adoption of the data protection law. A further delay was the fact that all documents had to be translated from Dutch or German so that Vince and the other English-speaking members of the team could read them.
Once Vince and the team had what they thought were all of the available case files （a false assumption, as they would later learn）， the next task was to look for new or overlooked evidence. They’d expected that most of the data would be in the Netherlands or Germany, but it turned out that they were wrong there, too. Because of the circumstances, participants, and outcome of World War II, important records and personal accounts （e.g., diaries, witness accounts, military records） were scattered across several continents. Postwar migration, confiscation of records by the Allies, and the establishment of Holocaust-related repositories had resulted in the vast dispersal of records and witness accounts. The team ended up scouring the globe, eventually finding records in Austria, Canada, Germany, Great Britain, Israel, Russia, the United States, and, of course, the Netherlands.
“We consulted twenty-nine archives,” Vince explained, “from the Simon Wiesenthal Center in Austria to the Library and Archives Canada to the Federal Archives in Germany and the UK National Archives at Kew.” He added, “This was no abstract journey. It was emotionally costly to confront the tragic history these archives preserved.”
Vince said he had been encouraged in his work by many cooperative people. “Our calls to institutions or witnesses were usually greeted by a comment that they’d heard or read about our investigation, wanted to assist, and were cheering for us to solve it.” The only institution that proved to be unhelpful was the Anne Frank Fonds in Basel, Switzerland. With his map of the relationships among the various stakeholders of the Anne Frank legacy, Jan van Kooten had been right to warn Thijs and Pieter that they would be entering a labyrinth very difficult to negotiate.
In the end, the search for new or overlooked evidence was not confined to the musty basements and vaults of archives and museums; the team went looking for interview subjects.
Of course, there was not much hope of locating direct witnesses, but they were able to find people tangentially related to the Annex raid. Vince particularly recalled the interview with an elderly Holocaust survivor whose parents and sister had gone into hiding in a house on the Prinsengracht and been betrayed a few months before the residents in the Annex. The raid had been the result of information from a notorious female informant, Anna “Ans” van Dijk. One of the policemen on that raid had also participated in the raid on Prinsengracht 263, and it was helpful to learn about the similarities between the two different operations.
Vince said that the team had searched for secondary witnesses who could have had conversations or first-person contact with direct witnesses or suspects, including relatives, friends, and neighbors. They had come up with a list of thirty people. Expanding outward, they constructed a separate list of nearly seventy informational witnesses, as Vince called them, who needed to be interviewed. They were people who conducted research, wrote for a publication, or were experts in a particular field that related to the investigation. That was the mind, training, and methodology of the FBI agent at work.
Once the flow of information and discoveries started, it was time for the team to employ modern law enforcement techniques that had not been available to the investigators at the time the crime was committed, such as behavioral science （profiling）， forensic testing, and artificial intelligence, defined as a computer system able to perform such tasks as visual perception, speech recognition, translation between languages, and decision making.