 Interrogated by kombrig Vasili Mikhaylovich Zarubin, Swianiewicz spoke fluent Russian and was apparently found useful.After the start of the Katyn Massacre in the spring of 1940, he was attached to a group of c. 100 Polish officers being moved by train to a small station in Gniezdovo near Katyn.There all of his comrades were massed in buses with blindfolded windows and transported to the mass murder site, while Swianiewicz himself was withdrawn from the transport.