A railway employee, Mourer joined the French Communist Party and was elected to parliament in April from the second constituency of Strasbourg. In a second round of voting, he defeated Georges Weill by 7,140 votes against 6,013. In parliament, he was a member of the committees on Algeria, colonies and protectorates, liberated regions, hygiene and economy.
In the 1936, he was re-elected in the second round with 5,844 votes.
In the fall of 1939, he was arrested along with other prominent Alsatian autonomists. In 1940, he was freed by German forces,  and was appointed as the Kreisleiter (Chief Administrator) of the Mulhouse district by the German authorities. His appointment as Kreisleiter materialized in spite of reservations from the Gestapo, who were reluctant to see a former communist occupy such a strategic office. During this period, he Germanized his name to 'Hans Peter Murer'.
After the war, the Court of Justice of Haut-Rhin sentenced him to death on February 26, 1947, for collaboration with the Germans. He was executed by a firing squad on June 10, 1947, on Île Napoléon.
Notably, evidence in Mourer's case focused primarily not on collaboration during the occupation itself but rather on the contacts he allegedly had with Germany prior to the war.
- Mourer (Jean Pierre)
- Goodfellow, Samuel. From Communism to Nazism: The Transformation of Alsatian Communists, in Journal of Contemporary History, Vol. 27, No. 2 (Apr., 1992), pp. 231-258
- Wieviorka, Olivier. Orphans of the Republic: The Nation's Legislators in Vichy France. Cambridge, Mass: Harvard University Press, 2009. p. 140
- Jean-Pierre Mourer (1897 - 1947)
- Wieviorka, Olivier. Orphans of the Republic: The Nation's Legislators in Vichy France. Cambridge, Mass: Harvard University Press, 2009. p. 328
- Béné, Charles. L'Alsace Dans Les Griffes Nazies. Raon-l'Étape: Fetzer, 52, rue Jules-Ferry, 1971. p. 272
- Raise the white flag: Conflict and collaboration in Alsace