Background: Josef Mengele (German: ['jo:zef 'meNG@l@]; 16 March 1911 - 7 February 1979) was a German Schutzstaffel (SS) officer and physician in Auschwitz concentration camp during World War II. Mengele was a member of the team of doctors responsible for the selection of victims to be killed in the gas chambers and for performing deadly human experiments on prisoners.
Context: In May 1960, Isser Harel, director of Mossad (the Israeli intelligence agency), personally led the successful effort to capture Adolf Eichmann in Buenos Aires. He hoped to track down Mengele as well so he too could be brought to trial in Israel. Under interrogation, Eichmann provided the address of a boarding house that had been used as a safe house for Nazi fugitives. Surveillance of the house did not reveal Mengele or any members of his family, and the neighborhood postman said that although Mengele had recently been receiving letters there under his real name, he had since relocated, leaving no forwarding address. Harel's inquiries at a machine shop where Mengele had been part owner did not turn up any leads either, so he had to give up.  In spite of having provided Mengele with legal documents in his real name in 1956, thus enabling him to regularize his residency in Argentina, West Germany offered a reward for his capture. Ongoing newspaper coverage of his wartime activities (accompanied by photographs of the fugitive) led Mengele to relocate again in 1960. Former pilot Hans-Ulrich Rudel put him in touch with the Nazi supporter Wolfgang Gerhard, who helped Mengele get across the border into Brazil. He stayed with Gerhard on his farm near Sao Paulo until more permanent accommodation was found with Hungarian expatriates Geza and Gitta Stammer. Helped by an investment from Mengele, the couple bought a farm in Nova Europa, and Mengele was given the job of manager. In 1962 the three bought a coffee and cattle farm in Serra Negra, with Mengele owning a half interest. Initially, Gerhard told the couple that Mengele's name was "Peter Hochbichler", but they discovered his true identity in 1963. Gerhard convinced them not to report Mengele's location to the authorities, saying they could themselves get in trouble for harboring the fugitive. West Germany, tipped off to the possibility that Mengele had relocated there, widened its extradition request to include Brazil in February 1961.  Meanwhile, Zvi Aharoni, one of the Mossad agents who had been involved in the Eichmann capture, was placed in charge of a team of agents tasked with locating Mengele and bringing him to trial in Israel. Inquiries in Paraguay gave no clues as to his whereabouts, and they were unable to intercept any correspondence between Mengele and his wife Martha, then living in Italy. Agents following Rudel's movements did not produce any leads. Aharoni and his team followed Gerhard to a rural area near Sao Paulo, where they located a European man believed to be Mengele. Aharoni reported his findings to Harel, but the logistics of staging a capture, budgetary constraints, and the need to focus on the nation's deteriorating relationship with Egypt led the Mossad chief to call a halt to the operation in 1962.
Question: What were the efforts?. Whats the answer?
), personally led the successful effort to capture Adolf Eichmann in Buenos Aires.