The Swiss Federal Intelligence Service has announced plans to release long-restricted records concerning the infamous Nazi war criminal Josef Mengele, though no specific timeline has been provided.

Mengele escaped Europe following the end of World War Two, yet persistent speculation suggested he may have visited Switzerland even while facing an international arrest warrant.

Researchers have sought repeated access to these records, but Swiss officials had consistently denied such requests until now.

Mengele served as a physician with the German Waffen SS and was assigned to the Auschwitz camp in occupied Poland, where he chose victims for the gas chambers. Roughly 1.1 million individuals perished there, among them nearly one million Jews.

Nicknamed the Angel of Death, he also picked out prisoners, especially children and twins, for cruel medical experiments before sending them to their deaths.

After the conflict ended, Mengele altered his appearance and adopted a new identity like many senior Nazis.

Using forged papers, he obtained Red Cross travel documents from the Swiss consulate in Genoa, Italy, enabling his flight to South America.

Although intended for war-displaced civilians, these documents were also secured by fleeing Nazis, an issue the Red Cross later acknowledged with regret.

What ties does Mengele have to Switzerland? Although he left Europe in 1949, he took a skiing trip to the Swiss mountains with his son Rolf in 1956, a fact known since the 1980s.

Officially he remained in South America thereafter.

Swiss historian Regula Bochsler questioned whether he returned after the 1959 international warrant was issued.

While studying Switzerland's possible role in aiding fleeing Nazis, Bochsler found that Austrian intelligence alerted Swiss counterparts in June 1961 that Mengele might be traveling under an alias within the country.

At the same time, his wife had leased a Zurich apartment and sought permanent residence there.

Evidence suggests Mengele considered a European journey in 1959, the historian noted to the BBC. Why rent an apartment in Zurich?

The modest suburban flat seemed odd given the family's resources, yet its location near the international airport raised questions.

Bochsler reviewed Zurich police files showing the apartment was monitored in 1961, with officers recording Mrs. Mengele driving her Volkswagen alongside an unknown man.

Could that man have been her husband?

Arresting a wanted criminal like Mengele in 1961 would have required federal involvement. In 2019 Bochsler requested access to those federal files from the Swiss Federal Archive.

Access was denied, with the records sealed until 2071 for security reasons and to protect family members.

Others faced similar refusals. In 2025 historian Gérard Wettstein also applied and was rejected.

The prolonged secrecy appeared pointless, he told the BBC, as it only encouraged speculation that authorities had something to conceal.

Wettstein took the matter to court, funding the effort through public donations that quickly reached 18,000 Swiss francs.

This prompted the Swiss Federal Intelligence Service to reverse course. A recent statement indicated access would be granted but under conditions still to be determined.

Some experts doubt the files contain significant details about Mengele himself.

Sacha Zala, head of the Swiss Society for History, believes there is little direct information on Mengele but possible references to foreign intelligence contacts.

By the late 1950s Israel's Mossad was pursuing fugitive Nazis, and Zala suspects Swiss authorities may have communicated with them, explaining the secrecy around foreign agency data.

Yet mentioning Mossad activities from seventy years ago hardly seems sensitive today.

Zala views the classification process as flawed and lacking historical context, which only fuels further speculation.

Historian Jakob Tanner notes the secrecy reflects Swiss attitudes more than it reveals about Mengele, highlighting tensions between security concerns and openness to the past.

Tanner participated in the 1990s Bergier Commission that investigated Switzerland's wartime ties to Nazi Germany, including the conduct of Swiss banks.

He understands the country's lingering discomfort over its wartime actions, such as rejecting Jewish refugees and retaining assets of Holocaust victims. Keeping such files closed undermines democratic principles, he argues.

Still, Tanner considers it credible that Mengele visited Switzerland in 1961.

Following the 1960 Mossad capture of Adolf Eichmann in Argentina, other Nazis in South America feared similar risks and may have sought refuge in Europe among relatives.

Tanner notes that another fugitive, Walter Rauff, spent time in Germany in 1960 despite being wanted.

One Bergier Commission member briefly examined portions of the Mengele files in 1999 and found no conclusive proof of his presence. The records were then resealed, and that researcher has since passed away.

No release date has been set, and references to future conditions concern Wettstein, who fears heavy redactions will limit transparency.

Bochsler shares those worries, suspecting extensive blackouts similar to other high-profile cases. She questions why the files remained closed for so long.

Mengele remained a figure of mystery and rumor for years.

He was never captured or tried for his crimes. He died in Brazil in 1979 under an assumed name.

Speculation persisted until his body was exhumed in 1985 and confirmed through DNA testing in 1992.

The doctor from Auschwitz was finally identified.

Yet questions linger about any Swiss visits. Did authorities overlook him, ignore his presence to avoid embarrassment, or is the entire story unfounded?

Perhaps the full truth will remain elusive, Wettstein concludes, but greater clarity may still emerge.