The Swiss Federal Intelligence Service (FIS) on 10 September published a 200-page dossier on the notorious Nazi war criminal Josef Mengele, the German doctor known as the “Angel of Death” for conducting cruel and often fatal medical experiments on prisoners at Auschwitz.
Mengele served at the Auschwitz extermination camp in Nazi-occupied Poland during World War II. According to the preserved documents, about 1.1 million people were killed at Auschwitz, around 1 million of them Jews.
He carried out brutal medical experiments on inmates, including children, under the guise of scientific research.
Postwar, Mengele obtained a Red Cross travel document under a false identity, allowing him to leave Europe.
Like many former Nazi officials, he spent years in hiding in Latin America while being pursued internationally for his crimes. After the war ended, he fled to South America. In 1979, he drowned in a swimming accident.
However, the documents released by Swiss authorities last week include materials provided to police suggesting that Mengele may have returned to Switzerland after initially fleeing Germany, or may have been planning to enter the country under a false name, according to the German news agency dpa.
On Thursday, FIS announced that it had wrongly refused access to the dossier. It stated that it had assumed the protection period, which had been extended under archiving law, would run until the end of 2071.
In February 2026, historian Gérard Wettstein appealed the FIS’s most recent refusal of access to the Federal Administrative Court. During the appeal proceedings, further checks with the Swiss Federal Archives established that the Mengele dossier had been evaluated by the Bergier Commission and therefore fell under the Federal Council’s liberal-access policy. The FIS issued a new decision on September 8, 2026, releasing the dossier with certain passages redacted.In 2001, when the then police service of the Office of the Attorney General handed the 217-page dossier over to the Federal Archives, the government had in fact adopted a liberal access policy. The Independent Commission of Experts on Switzerland and the Second World War, known as the “Bergier Commission”, had already examined the dossier for its report.
See more: The Dark Legacy of Nazi Medical Experiments: What We Must Never Forget
However, it is stated that it was not apparent to the FIS that the Mengele dossier had, in effect, already been declassified.
The FIS said there was no list identifying the files covered by the 2001 decision, and the relevant archive records were not marked accordingly. As a result, it had not known that the Mengele dossier fell under the Bergier Commission’s liberal-access rules.
The dossier contains numerous newspaper reports, most of which focused on the suspicion that Mengele had stayed in Switzerland on several occasions – even while he was still the subject of an international arrest warrant.
Earlier reports cited in connection with the dossier said Mengele had entered Switzerland in 1956 under the false name “Dr. Helmut Gregor”; an arrest warrant was issued against him three years later.
It also contains police reports, parts of which have been redacted. The FIS said it had kept redactions to a minimum, protecting information covered by statutory source-protection rules and certain personal data belonging to federal employees and third parties. These include entry bans and arrest warrants against Mengele, as well as police reports on investigations into suspects who may have provided Mengele with a hiding place.
The historian Gérard Wettstein, who had lodged the complaint, expressed his delight back in May in a report on Swiss Public Television SRF’s Tagesschau news programme at this “important step”, which would make it possible to dispel myths about Mengele’s stays in Switzerland.
The FIS said it would also review its access practices for archived records more generally, with the Swiss Federal Archives involved in the process.
(Rh/MF/MSM)