After a short stay in various Soviet prisons and POW camps, at the end of 1939 he was transferred to the NKVD Special Camp in Kozelsk. Smorawiński left the camp on 7 April 1940. Together with most of the Polish officers imprisoned there he was executed by the NKVD at Katyn, in the spring of 1940, aged forty-six, in what became known as the Katyn massacre. During the exhumation of 1943 his body was exhumed and identified, as one of the Polish generals to be identified. Among the Katyn victims were 14 Polish generals including Leon Billewicz, Bronisław Bohatyrewicz, Xawery Czernicki (admiral), Stanisław Haller, Aleksander Kowalewski, Henryk Minkiewicz, Kazimierz Orlik-Łukoski, Konstanty Plisowski, Rudolf Prich (murdered in Lviv), Franciszek Sikorski, Leonard Skierski, Piotr Skuratowicz, and Alojzy Wir-Konas.