The Polish government for the first time placed responsibility on the Soviet Union for the World War II Katyn massacre of more than 4,000 captive Polish officers. “We think everything indicates that the crime was committed by the Stalinist NKVD (secret police),” government spokesman Jerzy Urban told a news conference in Warsaw. Poland’s Communist rulers had claimed--as the Soviets maintained--that the Germans committed the massacre at Katyn Forest near Smolensk. But researchers have determined that the officers were killed before they could have fallen into German hands. The dead officers were among 15,000 seized by Soviet troops invading Poland in September, 1939, at the start of the war.