Argentina’s newly opened intelligence archives provide a detailed picture of how Josef Mengele — the Auschwitz doctor known for killing prisoners through medical experiments — spent years living comfortably in South America after World War II.

The documents, released earlier this year under President Javier Milei’s declassification initiative, reveal that authorities possessed extensive information on his activities but rarely acted on it.

Material in the files shows that by the time Argentina registered him as an immigrant in 1950, officials already had enough records to identify him as the same SS commander who selected victims at Auschwitz and carried out lethal procedures on twins.