 Complete the following phrase:  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 