Swiss intelligence releases long-sealed dossier on Nazi doctor Mengele

Switzerland has published a 217-page intelligence dossier on Josef Mengele, exposing how a long-standing error kept records about the Auschwitz doctor out of public reach. The Swiss Federal Intelligence Service placed the file online on September 10, 2026, after conceding that it had wrongly refused access.

Mengele became one of the most notorious perpetrators of Nazi medical crimes. At Auschwitz, he selected prisoners for experiments that were frequently cruel and fatal. After the war, he escaped to South America and remained a fugitive until his death in Brazil in 1979.

The released material focuses on his links to Switzerland. It contains newspaper reports about alleged stays in the country, including periods when international arrest warrants remained active. Police documents record entry bans, arrest warrants and inquiries into people suspected of helping him hide.

The publication gives historians and the public direct access to records held by the Federal Archives. It also places Swiss intelligence procedures under scrutiny, because officials acknowledged that the barrier came from a mistaken reading of archival rules.

The FIS said it had assumed the dossier remained protected until the end of 2071. That interpretation collapsed after historian Gérard Wettstein challenged the latest refusal, issued in February 2026. The complaint prompted a review that revealed the agency had applied the archival protection rules incorrectly.

The mistake concerned the status of a file transferred to the Federal Archives in 2001 by the police service then operating within the Office of the Attorney General. By that time, the federal government had adopted a liberal policy on access to historical records. The Bergier Commission had also examined the dossier while preparing its report on Switzerland and the Second World War.

The FIS said it had not recognised that the Mengele file had effectively already been declassified. The admission has consequences beyond this single archive. It raises questions about how intelligence agencies classify older records, how agencies communicate with archivists and how applicants can challenge decisions when government files remain sealed.

The service now says it will conduct a general review of its policy for access to archived documents. That review could determine whether other records face similar delays.

The dossier documents repeated suspicions that Mengele entered Switzerland while wanted internationally. Much of the file consists of newspaper coverage tracking alleged visits and attempts to establish where the fugitive stayed. The reports provide a record of public concern as Swiss authorities dealt with a man already associated with mass murder and medical experimentation.

Police material adds a more formal layer. The documents include entry bans and arrest warrants, along with investigations into individuals who may have offered Mengele a hiding place. Some passages remain redacted, so the publication does not answer every question about who knew what, or when.

The file is particularly relevant to Switzerland because Mengele returned to Europe as a tourist after the war and came to the country. Earlier reporting by Swiss public media examined that episode and the circumstances surrounding his stays. The newly released documents may help researchers test accounts that have circulated for decades.

Wettstein, whose complaint prompted the review, welcomed the release in May, calling it an “important step”. He said access could help dispel myths about Mengele’s presence in Switzerland. The published record now allows that work to proceed against primary sources rather than speculation alone.