Russian courts have classified the vast majority of files in the Katyn massacre case, making it impossible to access information that could help find some 7, 000 Polish officers still missing.

In addition, a new book called Katyn 1940 by Polish author Eugenia Maresch also collects together much documentary evidence about how the Western powers reacted to the murders.

Polish captain Andrzej (Artur Zmijewski) says goodbye to his daughter before being shipped east by the Russians in the film Katyn