Other conspiracy theories point to the British , the German Abwehr intelligence agency or the Poles themselves , some of whom ( especially under the command of General Anders ) had shown animosity toward Sikorski for , at least from their point of view , his policy of " colluding " with Soviet Premier Joseph Stalin , which reached new heights by the Germans ' April 1943 discovery of mass graves filled with thousands of Polish prisoners of war murdered by the Soviets at Katyn Forest in 1940 . Most notably though , in 1967 the Holocaust denier David Irving published a book dedicated to this incident , and suggesting British complicity in the incident
Katyn Forest
Katyn massacre
Władysław Sikorski's death controversy