"The Katyn massacre, also known as the Katyn Forest massacre (Polish: zbrodnia katyńska, 'Katyń crime'), was a mass murder of thousands of Polish military officers, policemen, intellectuals and civilian prisoners of war by Soviet NKVD, based on a proposal from Lavrentiy Beria to execute all members of the Polish Officer Corps. Dated March 5, 1940, this official document was then approved (signed) by the entire Soviet Politburo including Joseph Stalin and Beria. The number of victims is estimated at about 22,000, the most commonly cited number being 21,768" -- http://en.wikipedia.org/wiki/Katyn_massacre