Mossad’s Failed 1960 Hunt for Mengele

Mossad’s Failed 1960 Hunt for Mengele was an attempt to capture Josef Mengele in the immediate aftermath of Adolf Eichmann’s seizure in Buenos Aires. The plan depended on a narrow window: Mossad intended to use Eichmann’s interrogation to locate Mengele, then seize him before the plane carrying Eichmann to Israel departed. Instead, the clues led agents to addresses Mengele had already abandoned. The operation ended without his capture, while his move to Paraguay and the protection available there made the failure part of a longer international struggle over extradition and accountability.

Background: A Fugitive Network and a Delayed Warrant

The search took place in a South American refuge sustained by overlapping personal and political networks. Under Juan Perón, Argentina had welcomed thousands of Nazis, Fascists, and collaborators, while government-backed escape routes connected officials, diplomats, and other intermediaries. In Buenos Aires, former Nazi and Fascist figures formed a broad community in which fugitives could find contacts and support. Mengele had entered this environment under the name Gregor and cultivated relationships with people who could help him navigate the city. His circle included Willem Sassen and Eberhard Fritsch; after meeting them aboard the Falken, he moved among gatherings of prominent Nazi associates. Such connections formed the background to a hunt in which intelligence about a person’s name or former address could quickly become outdated.

The legal pursuit had begun before Mossad’s 1960 operation. Hermann Langbein, an Austrian survivor of Dachau and Auschwitz, had investigated Mengele and gathered evidence against him. On February 25, 1959, a prosecutor in Freiburg im Breisgau issued an arrest warrant charging Mengele with multiple cases of premeditated murder and attempted murder. Langbein pressed for the West German government to seek his extradition from Argentina, but the request had to pass through a chain of ministries, courts, and officials. Meanwhile, information about Mengele’s location pointed to Buenos Aires, even as the legal process moved slowly.

By November 1959, Mengele had obtained Paraguayan citizenship, along with a residence permit, a certificate of good behaviour, and an identity card. His citizenship application was facilitated by Hans-Ulrich Rudel, who intervened with Paraguayan officials as extradition requests approached. The West German request was forwarded to Buenos Aires, and another was expected in Asunción, but the process was burdened by delay and administrative obstacles. This change of jurisdiction mattered directly to Mossad’s plan: by the time the agents set out to find him in Buenos Aires, Mengele was living in Paraguay.

The Plan and Eichmann’s Interrogation

Isser Harel, Mossad’s director, was preparing a second capture operation while the agency pursued Eichmann. He had only scattered, dated information about Mengele: he was reportedly using the name Gregor and running a furniture factory in central Buenos Aires. Harel planned to use the Eichmann operation as an opening. After Eichmann’s capture, his agents would have nine days to find Mengele and bring him onto the aircraft scheduled to carry Eichmann back to Israel.

Mengele, however, had recently been moving between Paraguay and Argentina. At the beginning of 1960, he stayed for several days at a guesthouse in Vicente López, where Martha and Karl-Heinz were living. In April, the family met at the Hotel Tirol in Encarnación with Hans Sedlmeier to discuss money, communications, and the development of their Paraguayan subsidiary company. Mengele showed his partner photographs of a property he hoped to buy in the Alto Paraná region, then returned to the farm of Alбan Krug reassured by Martha’s willingness to follow him into exile. These movements placed the guesthouse in Mossad’s later trail, but did not make it a current address.

In early May, Mossad commandos arrived in Buenos Aires, and Harel carried Mengele’s coded file with him. On May 11, the agents seized Eichmann. During their interrogation, they asked whether he knew Mengele, where he was hiding, what he looked like, and whom he saw in Buenos Aires. Eichmann initially refused to provide information, despite pressure from his captors. He eventually gave them the address of the Vicente López guesthouse. The intelligence was concrete, but not current: by the time Mossad acted on it, the family had already left.

The Search Fails

Harel sent two agents to the guesthouse, an isolated villa behind a palisade at the end of a narrow street. Its position made it difficult to watch without attracting attention. The manageress said she knew neither a man named Gregor nor anyone named Mengele. A postman offered a trace: a Mengele family had lived there, but had disappeared a few weeks earlier without leaving a forwarding address. At the furniture factory, no one recognized a German called Gregor. Each lead pointed toward a real part of Mengele’s former life in Buenos Aires, yet none established where he was now.

The delay heightened the pressure but did not resolve the central problem. Harel considered raiding the guesthouse, convinced that Mengele might have returned, but his agents discouraged the move because it could jeopardize the operation. The available information suggested a target and a past address, not a reliable present location. Mengele was in Paraguay, outside the immediate search area, and the team could not turn the dwindling nine-day window into a confirmed lead.

On May 20, an El Al plane left Buenos Aires for Tel Aviv with Eichmann aboard, drugged and dressed as a member of the air crew. Mengele was not on the plane. Harel told his men that they would pursue him and that a new special unit would be created to track down Nazis, with Mengele as its first target. The declaration marked the end of this particular attempt, not the end of the hunt: Mossad had failed to locate him before Eichmann’s departure, and would have to resume the search on different terms.

Aftermath: Borders as Shelter and Obstacle

The escape from the Buenos Aires search was part of a wider contest among fugitives, investigators, and governments. Paraguay’s citizenship decision gave Mengele a legal status that its president, Alfredo Stroessner, could invoke against extradition. In later years, West German authorities focused their efforts on Paraguay, believing Mengele might be in Asunción or the Alto Paraná region. Stroessner resisted their demands, defended Paraguayan sovereignty, and disputed claims about whether Mengele remained in the country. In 1964, West Germany publicly stated that Mengele was a Paraguayan citizen who lived in the tri-border area and often travelled to Brazil; Paraguay continued to deny that it could deliver him.

The failed 1960 search thus revealed more than an intelligence error. Mossad’s plan relied on a brief interval, a set of old identifiers, and a Buenos Aires address supplied by a prisoner who ultimately disclosed what he knew. Mengele’s own movements, his network of helpers, and the legal protection of a newly acquired nationality worked against the operation. The border that had carried him away from the search also complicated the pursuit that followed: locating him was inseparable from the questions of which government would act, which would refuse, and how long a fugitive could remain beyond the reach of law.