Poland has experienced two cruel systems. One of them was fascism, symbolized by the German Nazi concentration camps at Auschwitz-Birkenau. The second one was Stalinism, Katyn will remain its symbol forever. For over 50 years, no other issue in Polish-Soviet relations was as concealed as the Katyn massacre. In this essay, I will talk about the genocide in 1940 on 22,000 Poles (soldiers and civilians), investigations in this matter, and the fight for the truth. Everyone knew that any public statement about this crime could have significant consequences, such as dismissal from work or school expulsion. The Katyn genocide was a war crime that was first concealed and then distorted for the longest time. It can be said that it was a crime against the Polish nation.