The archival-investigative case of Vasyl Prokhoda, a Ukrainian military, public and political figure, Lieutenant Colonel of the Ukrainian People's Republic Army, military historian, is analyzed, as it is not only an important source for studying his life but also for studying totalitarianism in the Ukrainian SSR and the USSR. The investigation clarified the circumstances of the detention and arrest of V. Prokhoda in late January - early February 1945, the vicissitudes of the investigation from February 2, 1945, to September 10, 1945. Working methods of employees of the SMERSH counterintelligence administrative departments are highlighted. Some facts of V. Prokhoda's biography are characterized: his participation in the Ukrainian revolution of 1917–1921, public activity during emigration to Czechoslovakia, work in construction companies during World War II. The author analyzed topics of questions of interest to investigators: military service in the Russian tsarist army on the eve and beginning of World War І; national-cultural activities in POW camps in the Austro-Hungarian Monarchy; participation in Ukrainian military structures during the Ukrainian Revolution of 1917–1921; struggle against the Bolshevik government in Ukraine; activities in public societies and organizations in exile in Czechoslovakia and Germany (as «Sokil», «Society of Former Soldiers of the Ukrainian People's Republic Army», «Ukrainian National Union»); work in construction companies «in favor of Germany» during World War ІІ; information on the activities of the emigration government of the Ukrainian People's Republic and relations with its leaders; «counter-revolutionary nationalist» activities of the leaders of Ukrainian emigrant organizations. The facts of V. Prokhoda's biography in the archival-investigative case and his memoirs «Zapysky nepokirlyvoho» («Notes of the Rebellious») are compared. Keywords: Vasyl Prokhoda, Ukrainian People's Republic, archival-investigative case, public activity, SMERSH, People's Commissariat for Internal Affairs.