He was arrested by the Gestapo in 1939 and imprisoned until 1945 in various concentration camps. After the war he was branded as a Trotskyist and accused of being the member of a supposed plot to overthrow the Communist regime. He was sentenced to death along with his co-defendants, Milada Horáková, Jan Buchal and Oldřich Pecl, on 8 June 1950, and executed by hanging.