Mossad agents twice located the notorious Nazi doctor Josef Mengele when he was in hiding in South America in the 1960s but chose not to arrest him and bring him to face justice, according to documents unsealed this week in Israel.

The Nazi's "angel of death" fled to Latin America at the end of the Second World War, attempting to escape inevitable prosecution for war crimes perpetrated predominently at Auschwitz. Mengele oversaw the gas chambers at the concentration camp and carried out a program of sadistic experiments on Jewish and Roma inmates, particularly children.

Despite his prominent role in the Holocaust, Mengele died a free man in Brazil in 1979. But he could have been captured for the first time in 1960 when officers in Israeli's national intelligence agency located him in Bueno Aires. 

According to documents given by Mossad to the Yad Vashem Holocaust Memorial in Jerusalem, and reported in The Times, a senior agent decided to focus resources on apprehending Adolf Eichmann, a chief organiser of the Nazi genocide.

Eichmann was caught in Argentina and brought to Israel in 1960, where he was convicted of war crimes and hanged.

Mossad’s then director, Isser Harel, was persuaded not to try capturing both men by the team leader on the ground, Rafi Eitan. Mr Eitan, who is now 90, told Israeli public radio: “I didn’t want to carry out two operations at the same time because we had one successful operation in the bag, and in my experience if you try to carry out another one you put them both at risk.”

Mengele fled to Brazil after learning of Eichmann's arrest, but was tracked down again by Mossad in 1962. The documents reveal that Israeli authorities discussed a kidnap attempt but dismissed them for political reasons.

Mengele lived out the rest of his years in Brazil - reportedly returning incognito to West Germany at least once - before dying of a stroke in Sao Paulo aged 67.