In the last phase of the camp operations , all prior mass graves were unearthed by a mechanical digger . It was the result of direct orders from the Nazi leadership ( possibly from Himmler ) , soon after the Soviet Katyn massacre of 22,000 Polish soldiers was discovered in Russia . At Katyn , the German-led exhumations by the international Katyn Commission revealed details of the mass murder by examining preserved bodies . The Germans attempted to use the commission 's results to drive a wedge between the Allies . All corpses buried at Belzec were secretly exhumed and then gradually cremated on long open-air pyres , part of the country-wide plan known as the '' Sonderaktion 1005 '' . Bone fragments were pulverized and mixed with the ashes to hide the evidence of mass murder . The site was planted with small firs and wild lupines and all camp structures were dismantled
Katyn massacre
Katyn massacre
Belzec extermination camp