Abstract: The aim of this paper is to analyze the extradition processes against Gustav Wagner, a Nazi criminal arrested in Brazil. Wagner worked at the Hartheim Euthanasia Center and was the deputy commandant of the Sobibor extermination camp, known for his cruelty and for having killed personally dozens of persons of Jewish origin. After the war, he escaped from Europe with the aid of members of the Catholic Church and, after a period in East Asia, he fled to Brazil. He was arrested in Brazil in 1978 and had his extradition requested by the Federal Republic of Germany, Austria, Poland and Israel. The Brazilian Supreme Court denied his extradition. The research focused, at first, on analyzing Wagner and his crimes, then on describing how he was found and arrested in Brazil, allowing for the study of his extradition processes and their outcome. Specific bibliography, interviews with survivors from the Sobibor extermination camp, his extradition processes, and newspapers of the time were used as research material. These steps were taken to answer the main research question : What were the legal reasons that underlay the denial of Wagner’s extradition in that historical moment? It may be concluded that the extradition was rejected because of the strictly legal analysis made by the Brazilian Supreme Court in the Wagner case, despite the international laws against criminals that participated in genocide.