Switzerland releases digital files on Josef Mengele to public with 'as little as possible' redacted

Switzerland’s Federal Intelligence Service (NDB) published the Josef Mengele file on Thursday. A digital version of the file, which is held in the Federal Archives in Bern, was uploaded to the government website for public access, although parts of it were redacted. The original document remains in the archives.

A statement from Bern said that after a historian requested access to the file, the intelligence service received many additional requests. In light of the “exceptionally high public interest,” the authorities decided not to limit access to individual reviews at the archives, but instead publish the file online. However, they emphasized that wherever protections applied to sources or the personal details of third parties, “there was no room for maneuver,” and the information was redacted.

According to the official statement, “as little as possible” was redacted: the names of current and former government employees connected to the service and its predecessors, protected information about sources, and personal details of private individuals. Public figures were not redacted. The service said the documents remained readable as a whole and that the course of events could be understood from them.

The file was originally compiled by the Federal Prosecutor’s Police Service, the predecessor of the intelligence service, and transferred to the archives in 2001. Under Swiss archival law, it was supposed to remain classified until the end of 2071. Requests for access were repeatedly rejected, with the latest denial coming in February 2026. A historian appealed the decision to the Federal Administrative Court.

During the proceedings, it emerged that the file had previously been reviewed by the Bergier Commission, which investigated Switzerland’s ties with Nazi Germany. Materials examined by the commission were subject to a government decision from December 7, 2001, instructing authorities to adopt a more liberal policy on access to documents. In May, the service announced that it would reconsider its refusal. On September 8, a new decision was issued, and on Thursday the file was uploaded online.

Mengele suspected of passing through Switzerland

Mengele, the SS doctor known as the “Angel of Death of Auschwitz,” was responsible for selections and medical experiments at the camp. After the war, he fled to South America and was never brought to trial. He died in Brazil in 1979.

At the center of interest in the Swiss file is a long-standing suspicion: that in 1961, after West Germany issued an arrest warrant against him, Mengele visited the Kloten area near Zurich Airport. His wife, Martha, rented an apartment in the area, and police monitored her. Historians hope the file will clarify what Swiss authorities knew at the time and whether the war criminal passed through the country without being arrested.

Even before the file was published online, historians sharply criticized the manner of its release. Instead of allowing access to the original documents, the intelligence service chose to publish a redacted digital version. Swiss newspapers reported that researchers described the move as “scandalous” and argued that it damaged Switzerland’s reputation.

Historian objects to continued classification of Mengele file

Historian Gérard Wettstein, who fought to open the file and raised public funds to finance his appeal, warned in recent months that heavy redactions would undermine the goal of transparency. After the publication, he said that keeping the file closed until 2071 “feeds conspiracy theories,” and that as long as parts remain classified, the public will continue to believe there is something to hide. According to reports in Switzerland, he is considering another appeal to demand access to the original documents.

The intelligence service itself acknowledged in its official statement that the file remains subject to a strict confidentiality period and that the case is now serving as a basis for a broader review of access policies for archival documents in general.

The Swiss disclosure comes after another dramatic release in December 2025. Argentine President Javier Milei ordered the publication of about 1,850 documents on Nazis who fled to South America after World War II. Among the files was a detailed dossier on Mengele.

The Argentine documents revealed that Mengele entered the country in 1949 using a fake passport under the name Helmut Gregor, but that by the mid-1950s Argentine authorities already knew his true identity. In 1956, he requested his original birth certificate from the West German Embassy in Buenos Aires and began using his real name. He lived in the Buenos Aires suburb of Carapachay, married his brother’s widow, and even partnered in a medical laboratory. In 1959, an Argentine judge rejected Germany’s extradition request, citing “political persecution.” He later fled to Paraguay and from there to Brazil.