In 1952, and again in 1954, the Military Tribunal of Lyon sentenced him to death in absentia.

Having settled in La Paz under the assumed name of Klaus Altmann, Barbie took Bolivian nationality. He became a businessman while playing an active role in the political police of the Bolivian military dictatorships.

In June 1971, the Munich Public Prosecutor's Office decided to close the case on the grounds that it was impossible to prove that Barbie knew what fate awaited the people he had arrested. It was a German woman, Beate Klarsfeld, who got the Jewish community and members of the Resistance mobilized again to fight this denial of justice. She found the decisive witnesses required to resume the Munich investigation. With the help of a German living in Lima, she was able to establish the true identity of Klaus Altmann, who had just moved to Peru. However, when she arrived in Lima, he ran off to La Paz. There, she mounted a campaign for his extradition.

With the help of Regis Debray and Gustavo Sanchez, a former Bolivian prefect in exile, Serge Klarsfeld devised a plan of capture. This plan failed but, nine years later, the same people succeeded in carrying through the legal procedure by means of which Klaus Barbie lost his Bolivian citizenship. Expelled from Bolivia, Barbie was flown to French Guiana where he was arrested.

-the liquidation of the Lyon committee of the Union générale des Israélites de France (UGIF), following the roundup of February 9th, 1943 (79 concentration camp prisoners, 6 survivors) ;
-the arrest of the 44 Izieu children and of the adults in charge of them ;
-the imprisonment in concentration camps of approximately 650 people who were transported in the last convoy to leave Lyon, on August 11th, 1944.
- the torture and putting to death of Marcel Gompel, a Jewish member of the Resistance, professor at the Collège de France, and the imprisonment in concentration camps of members of the Resistance. In December 1985, a decision of the Court of Cassation stipulated that the deportation of these people to concentration camps was not directly related to the war conflict This action went beyond the bounds of war crimes and should be considered a crime against humanity. Accordingly, the victims were able to associate in a court action with the public prosecutor.

Barbie, who chose not to attend most of the hearings, did not acknowledge any of these crimes.

On June 29th, 1987, Public Prosecutor Pierre Truche gave his closing speech for the prosecution, asking that the defendant be sentenced to life imprisonment.

On July 3rd, 1987, the verdict of guilty, with no extenuating circumstances, was given. Barbie was sentenced to life imprisonment.

On September 25th, 1991, Klaus Barbie died from cancer in prison.