The Swiss Federal Intelligence Service announced this month that it will reveal previously sealed files on the Nazi war criminal Josef Mengele, without specifying when, the BBC reported on Saturday.
Mengele, the doctor known as the Angel of Death, ran a system of experiments on Auschwitz camp prisoners, including severe torture of twins and people with disabilities, exploiting his professional status to advance Nazi racial theory.
Mengele evaded punishment for decades until his accidental death in 1979.
Although historically Mengele's interaction with Switzerland has been considered minimal, with a skiing visit in 1956 with his son as the most prominent publicly known connection, Swiss historian Regula Bochsler told the BBC that there was some evidence he'd been planning a trip to Europe, possibly including Switzerland.
Crucially, this trip would have occurred sometime in 1959, after an international warrant was issued for Mengele's arrest.
Bochsler explained that she had learned the Austrian intelligence service had warned Switzerland in 1961 that Mengele might have entered its territory under an assumed name.
She had also learned that Mengele's wife had applied for permanent residency and rented an apartment in Zurich during that timeframe.
In 2019, Bochsler petitioned the Swiss government for access to confidential files related to Mengele's history in the country, but was rebuffed. Another historian, Gérard Wettstein, tried again in 2025, with similar results. The files, they were both informed, were sealed until the year 2071.
"It seemed ridiculous," Wettstein told the BBC. "As long as they are closed until 2071, it fuels conspiracy; everyone says 'they must have something to hide'."
The Swiss Federal Intelligence Service finally changed its mind after Wettstein took them to court, stating that "The appellant will be granted access to the file, subject to conditions and requirements yet to be defined."
'The administration fueled conspiracy theories'
President of the Swiss Society for History, Sacha Zala, does not believe that there will be anything relevant about Mengele in the files, instead telling the BBC that he thinks there may be references to foreign intelligence services and informants, such as the Mossad.
"It shows the stupidity of the declassification process without historical knowledge," Zala said. "In this way, the administration fueled conspiracy theories."
Jakob Tanner, another historian, said that the secrecy surrounding the files represented "a conflict between national security and historical transparency, and the former often prevails in Switzerland."
"It is a problem for a democratic state that these files are still closed," he argued.
Wettstein and Bochsler both expressed concern that, even once the files were released, they would be heavily redacted.
"I fear we will get a file that is more black than transparent," Wettstein said, while Bochsler compared the release to that of the Epstein files, asking, "Why have these Mengele files been closed for so long?"
"Maybe we will never get to the real truth," says Wettstein. "We will never know if he was here or not… but maybe we can have at least a clearer idea."
Dr. Itay Gal contributed to this report.