The arrest warrant and manhunt for Josef Mengele unfolded across Europe and South America, exposing how legal jurisdiction, diplomatic delay, and state protection could frustrate efforts to prosecute a fugitive accused of murder. Beginning with the investigations of survivor Hermann Langbein, the pursuit produced a West German warrant in 1959, but Mengele escaped to Paraguay and acquired citizenship before extradition could be secured. Later initiatives, including a proposed Mossad operation and a renewed international search in 1985, made his capture a test of whether postwar authorities would turn evidence and public pressure into accountability.

Evidence and the 1959 Warrant

Langbein had been a prisoner in Dachau and Auschwitz and was forced to serve as personal secretary to Auschwitz chief doctor Eduard Wirths. He did not accept that Mengele had simply disappeared. In 1954, a legal announcement of Mengele’s divorce gave him a lead; Langbein had already helped establish the International Auschwitz Committee in 1952 to seek compensation for survivors and gather testimony that could support prosecutions. He investigated discreetly, accumulated evidence, and came to believe Mengele was living in Buenos Aires, in part because an Argentine lawyer had been involved in the divorce proceedings.

Langbein sent his files to the West German federal minister of justice, who said the case belonged before a regional court. Most judges declined to act. In Freiburg im Breisgau, however, the prosecutor issued an arrest warrant on 25 February 1959, alleging multiple cases of premeditated murder and attempted murder. Freiburg was Mengele’s last registered address: he had used it when helping Irene settle there at the end of the war. Langbein then pressed for the Ministry of Foreign Affairs to seek Mengele’s extradition from Argentina.

The evidence behind the pursuit concerned Mengele’s conduct at Auschwitz, not merely his flight afterward. Hungarian Jewish prisoner and doctor Miklós Nyiszli, who had been compelled to assist Mengele, recorded the selections and forced experiments in a survivor’s account. His testimony described Mengele’s role in directing arriving deportees to death or forced labor, as well as experiments on twins and the transfer of organs to the research institute directed by Otmar von Verschuer. Nyiszli also recalled Mengele continuing his research in the dissection room in 1944. Such testimony gave the pursuit a human and evidentiary basis against Mengele’s later effort to present his conduct as medical duty.

Escape and Paraguayan Citizenship

A police informant alerted Hans Sedlmeier to the warrant, and Sedlmeier relayed the news to Mengele by telegram. With extradition now a possibility, Mengele sold his villa and shares in Fadro Farm, closed his bank accounts, and fled to Paraguay. He was distressed as he packed scientific journals into a cardboard box and left his pharmaceutical-laboratory partners without explanation. Martha and Karl-Heinz could remain in Argentina, but were told to move discreetly; Mengele said they would meet soon in Asunción.

Hans-Ulrich Rudel helped arrange a refuge and supported Mengele’s application for Paraguayan citizenship. The lack of an extradition treaty between West Germany and Paraguay, together with President Alfredo Stroessner’s insistence that Paraguay would not surrender its citizens to foreign powers, offered a powerful defense against extradition. Rudel also sought a rural hiding place in a German community and turned to Alban Krug, who owned a farm in the Nueva Bavaria enclave near the Argentine border. The citizenship application was unlawful: an applicant was supposed to have lived in Paraguay for five years. Nevertheless, in November 1959 the Supreme Court granted Mengele citizenship, a residence permit, a certificate of good behavior, and an identity card.

Meanwhile, the extradition process crossed a chain of institutions in Argentina, including the Foreign Ministry, the Senate president, the attorney general, a federal judge, police, and tribunals. The German ambassador, Junker, procrastinated, and the procedure accumulated legal obstacles and delay. In Paraguay, Interpol’s request for a copy of Mengele’s naturalization file alerted the Interior Ministry and police to the expected request. Rudel intervened with the minister, presenting Mengele as a political target who could be useful to Paraguay. The contrasting pace mattered: while Argentina’s request moved through a slow administrative process, Mengele’s citizenship was secured.

International Pursuit and Political Obstacles

The planned abduction of Adolf Eichmann created a second possible route to Mengele. Mossad director Isser Harel wanted to add Mengele to the operation: using the limited information that he was known as Gregor and supposedly ran a furniture factory in central Buenos Aires, Harel planned to give his men nine days after Eichmann’s scheduled capture on 11 May 1960 to find Mengele and bring him to the plane taking Eichmann to Israel. The plan was an intention, not evidence that the second capture occurred.

Eichmann’s capture nevertheless transformed the atmosphere around the fugitive Nazi community. Journalists went to Buenos Aires, and the kidnapping became a humiliation for Argentina and a challenge to West Germany’s efforts to show that it would confront its past. On 20 June, another warrant for Mengele’s arrest was issued. Nazi groups in Buenos Aires began to fracture; Willem Sassen’s associates suspected him of betraying Eichmann, and Sassen sold his recorded interviews to Life and European media before fleeing to Uruguay. The wider hunt made Mengele’s concealment more precarious, even as he remained beyond the reach of the authorities.

West Germany’s later efforts were hampered by limited investigative commitment and procedural delay. The authorities took more than a year to send fingerprints to their South American embassies, and the federal government sent neither agents nor spies to pursue Mengele. In 1962, Bonn requested his extradition from Paraguay, where officials believed he lived in Asunción or the Alto Paraná region. Stroessner refused to cooperate, having been told by Rudel that Mengele had left for Brazil; he also said Paraguay would refuse extradition if Mengele were arrested there. In 1963, Chancellor Konrad Adenauer offered Paraguay ten million US dollars in aid if it delivered Mengele, but Stroessner rejected the offer.

Pressure increased in 1964, while attention was focused on the Frankfurt Auschwitz trials. West Germany publicly stated that Mengele was a Paraguayan citizen living in the tri-border region and frequently travelling to Brazil. Its ambassador asked Stroessner to revoke the citizenship on the grounds that it had been fraudulently obtained. Stroessner insisted Mengele had long since left and denounced West German interference as an affront to Paraguayan sovereignty. Fritz Bauer then announced a reward of 50,000 marks for Mengele’s capture and said the fugitive was living freely under his real identity, wealthy and protected by influential friends. Paraguay’s interior minister claimed he was hiding in Brazil or Peru. A former SS officer arrested in Paraguay the following year said he had encountered Mengele there, but West Germany’s pursuit eventually eased as Bonn prioritized relations with Paraguay and its strategic importance in regional policy.

Survivor Testimony and Renewed Search

The pursuit returned to international prominence in 1985. On the fortieth anniversary of Auschwitz’s liberation, survivors who had been twins, dwarves, or disabled children in the camp called for Mengele’s capture. Their appeal was broadcast internationally. On 4 February, a three-day mock trial was held at Yad Vashem in Jerusalem, with the chief prosecutor from Eichmann’s Jerusalem trial, Nazi-hunter Simon Wiesenthal, and the chief US military counsel from the Nuremberg trials among those leading the tribunal. Former prisoners and other witnesses described Mengele’s experiments and abuse, including testimony from a former guard in the Gypsy Block and accounts by mothers whose infants had been subjected to his decisions. The proceedings were a mock trial, not a criminal judgment, but the testimonies carried the case to a worldwide audience.

The renewed attention had practical consequences. Before the mock trial ended, the US attorney general called for a review of the complete file and demanded Mengele’s arrest. A declassified American counterintelligence memorandum, released by the Simon Wiesenthal Center, incorrectly suggested that the United States had held Mengele in 1947; the error nevertheless provoked questions about whether American authorities had let him escape. The Office of Special Investigations coordinated the US inquiry with the CIA, the National Security Agency, and the Department of Defense. On 8 February, Israel announced that it would resume the hunt and offered a reward of one million dollars. The Simon Wiesenthal Center and the Washington Times each added a million dollars, while Germany offered a million marks. By then, the rewards totalled the equivalent of $3.4 million, and American, Israeli, and West German authorities were coordinating information. Journalists and adventurers descended on Günzburg and South America, searching for a man whose death was not yet known to them.