In 1968, the Mossad received fresh confirmation that Mengele was living on the farm near São Paulo, sheltered by the same people who had been under surveillance six years earlier. “We have never been so close to Meltzer,” a Mossad operative wrote to Amit, using Mengele’s code name. The operative asked permission to nab one of those people and torture him to find Mengele. But his superiors were worried by his eagerness, ordered him back to Israel and replaced him.

By then, Palestinian terrorism had become Israel’s main security challenge, and the Mossad devoted most of its efforts to that threat. For the next 10 years, backed by Eshkol and his successors as prime minister, Golda Meir and Yitzhak Rabin, almost nothing was done about Mengele. The surge in terrorism, the surprise Yom Kippur War in 1973 and the Syrian military buildup with Soviet assistance took precedence.

When Menachem Begin came to power in 1977, he wanted a change. He made that clear in an early meeting with Yitzhak Hofi, who was then the director of the Mossad. “When Begin came in, he thought that not enough was being done and that there was a need to go on hunting Nazis,” Hofi later said in a classified interview with the Menachem Begin Heritage Center. “I told him, ‘Prime minister, today the Mossad has other missions that concern the national security of the people of Israel today and tomorrow, and I give preference to today and tomorrow over yesterday.’ ” Begin didn’t appreciate that response. “In the end we decided that we would focus on one more target, Mengele, but Begin, who was a very emotional man, was disappointed,” Hofi said.

For Begin, getting to Mengele was not just a matter of the past. He equated Yasir Arafat with Hitler. “Unlike other Israelis, who saw the Holocaust as a one-time historical catastrophe,” said Shlomo Nakdimon, a prominent Israeli journalist who was close to Begin, “Begin believed with all his heart that the lesson of the Holocaust is that the Jewish people must protect themselves in their own country in order to prevent a renewed threat to their existence.”

Begin thought settling the score with Mengele would show Palestinian leaders (and the Israeli public) that they would have to pay a price for harming Israelis. His attitude was reflected in a message he sent to President Ronald Reagan when he sent the Israeli Army into Lebanon in 1982, saying that he felt as if “I have sent an army to Berlin to wipe out Hitler in the bunker.”

The prime minister wasn’t satisfied with Hofi’s verbal agreement to find Mengele. In July 1977, the cabinet’s security committee secretly approved a proposal from Begin “to instruct the Mossad to renew its search for Nazi war criminals, in particular Josef Mengele. If it is not possible to bring them to trial, to kill them.”

The pursuit resumed with a vengeance. In 1982, the agency even considered abducting a 12-year-old boy and threatening to take his life unless his father, Hans-Ulrich Rudel, a devoted Nazi and a childhood friend of Mengele’s, gave them the information that could lead to his capture. (In the end, Rudel died before the Mossad decided whether to go through with the operation.)