A member of the Italian resistance movement during World War II, Audisio was involved in the death of Benito Mussolini, and personally executed the dictator and his mistress Clara Petacci according to the generally accepted account of the event.

After spending some weeks in Casale Monferrato, where he helped organize partisan groups, he reached Turin and made contact with the National Liberation Committee (CLN) and the Piedmontese leadership of the Communist Party.

He carried out the execution of Mussolini, his mistress, and a number of high-ranking Fascists the following day in Giulino di Mezzegra, along with fellow partisan officers Aldo Lampredi and Michele Moretti.

[3] Some sources have questioned this version, alleging instead that the execution was carried out by Lampredi, Moretti or other partisans who were with him,[4][5][6] by British SOE officers,[7] by Luigi Longo,[8] or that Mussolini and Petacci committed suicide with cyanide capsules.

[9] In the following years, Audisio would also be the target of various disputes over secret papers or valuables that Mussolini had allegedly been carrying at the time of its arrest, the death of Petacci, and the public exhibition of the corpses in Piazzale Loreto.

His identity as "Colonel Valerio" was revealed in March 1947 by the conservative newspaper Il Tempo, and then subsequently confirmed by the Communist Party.