After the incorporation of the Sudetenland to the Third Reich as a result of the Munich Agreement, he became a member of the National Socialist Motor Corps (NSKK), a paramilitary organization of the Nazi Party.

[2] At the beginning of the Second World War, Suchomel was a tailor in the German Army and served in the Battle of France in 1940.

Here he was a member of Sonderabteilung Einsatz R (English: "Special Action Unit R"), involved in extermination of Jews, confiscation of Jewish assets, and fighting partisan activity.

[3] Twenty years after the end of the war, in the framework of first official investigations into crimes against humanity at the Treblinka extermination camp, German authorities collected evidence of Suchomel's participation in the Holocaust.

The charges consisted of the murder of at least 700,000 mainly Jewish people in the gas chambers, as well as deadly assault, shootings, and hangings of individual prisoners.

[1] Franz Suchomel was secretly recorded during an interview for the documentary film Shoah, directed by Claude Lanzmann and released in 1985.

During the interview at the Hotel Post in Braunau am Inn, he provided details of Treblinka criminal operations.