What actions occurred during the liberation of the camps that were specifically intended to formulate a case against the nazis?

As Allied troops moved across Europe in a series of offensives against Nazi Germany, they began to encounter tens of thousands of concentration camp prisoners. Many of these prisoners had survived forced marches into the interior of Germany from camps in occupied Poland. These prisoners were suffering from starvation and disease.

Soviet forces were the first to approach a major Nazi camp, reaching Majdanek near Lublin, Poland, in July 1944. Surprised by the rapid Soviet advance, the Germans attempted to hide the evidence of mass murder by demolishing the camp. Camp staff set fire to the large crematorium used to burn bodies of murdered prisoners, but in the hasty evacuation the gas chambers were left standing. In the summer of 1944, the Soviets also overran the sites of the Belzec, Sobibor, and Treblinka killing centers. The Germans had dismantled these camps in 1943, after most of the Jews of Poland had already been killed.