(Reuters) - Here are some details on the massacre of 22,000 Polish troops in the Katyn forest in 1940. Russian parliament on Friday approved a resolution blaming Soviet dictator Josef Stalin directly for the massacre.
-- Germany invaded Poland from the west in 1939, and Soviet forces occupied the eastern half of Poland. As a consequence of this occupation, tens of thousands of Polish military personnel fell into Soviet hands and were interned in prison camps inside the Soviet Union.
-- However after the Germans invaded the Soviet Union in June 1941, the Polish government-in-exile (located in London) and the Soviet government agreed to cooperate against Germany, and a Polish army on Soviet territory was to be formed.
-- When Poland requested the return of 15,000 prisoners of war from the Soviets, the Soviet government informed Poland in December 1941 that most of those prisoners had escaped to Manchuria and could not be located.
-- On April 13, 1943, the Germans announced they discovered the mass graves of Polish officers in the Katyn forest near Smolensk.
-- A total of 4,443 corpses were recovered. The fate of the remainder is still unknown. They had apparently been shot from behind and piled in stacks and buried. Investigators identified the corpses as the Polish officers who had been interned at the Soviet camp near Smolensk and accused the Soviet authorities of having executed the prisoners in May 1940.
-- The Soviet government then claimed that the Poles had been engaged in construction work west of Smolensk in 1941 and the invading German army had killed them after overrunning that area in August 1941.
-- However both German and Red Cross investigations of the Katyn corpses produced firm physical evidence that the massacre took place in early 1940, at a time when the area was still under Soviet control.
-- The Soviet government refused demands by the Red Cross to investigate, and in April 1943, the Soviets broke diplomatic relations with the Polish government in exile in London. The Soviet Union then set about establishing a Polish government-in-exile composed of Polish communists.
-- After blaming Nazi Germany for the Katyn massacre for decades, the Soviet Union admitted in April 1990 that its forces were responsible but none of the culprits has ever been identified and investigations have been shelved.
-- A Russian court in July 2008 refused to consider a request for a criminal investigation into the Katyn massacre. The families of some of the victims were trying to use the Russian courts to force prosecutors to launch a new investigation into a massacre seen in Poland as a symbol of the repression the country suffered under Soviet domination.
-- President Dmitry Medvedev has released new materials in a gesture of solidarity with Warsaw after Polish President Lech Kaczynski, his wife and 94 officials were killed on April 10 in a plane crash en route to a ceremony commemorating the massacre.
Writing by David Cutler, London Editorial Reference Unit;