At the Chełm prisoner-of-war camp, German officers from Operation Reinhard arrived one day and recruited 200 to 300 Ukrainians for military training as auxiliary police in the service of Nazi Germany within General Government.[1] They were sent to the Trawniki concentration camp SS training division, and Fedorenko was among them. At Trawniki, he was trained as a Hiwi shooter and was posted to Treblinka extermination camp.[2] Fedorenko became an NCO (Non Commissioned Officer) attaining the rank of Oberwacher and from September 1942 to August 1943,[4] he led a 200-member Ukrainian detachment which shaved, stripped, beat and gassed prisoners brought to Treblinka.[5]