Mengele's name was mentioned several times during the Nuremberg trials in the mid-1940s, but the Allied forces believed that he was probably already dead. Irene Mengele and the family in Günzburg also alleged that he had died. Working in West Germany, Nazi hunters Simon Wiesenthal and Hermann Langbein collected information from witnesses about Mengele's wartime activities. In a search of the public records, Langbein discovered Mengele's divorce papers, which listed an address in Buenos Aires. He and Wiesenthal pressured the West German authorities into starting extradition proceedings, and an arrest warrant was drawn up on 5 June 1959. Argentina initially refused the extradition request because the fugitive was no longer living at the address given on the documents; by the time extradition was approved on 30 June, Mengele had already fled to Paraguay and was living on a farm near the Argentine border.