The Nazis' vast concentration camp network and, later, the 'Final Solution' programme made heavy demands on the SS whose responsibility it was. The use of 'overseers' minimised costs and enabled the camps to run with fewer SS personnel. As this well researched book describes, there were three principal groups of 'helpers' Sonderkommandos, Kapos and Trawniki.
The Sonderkommandos' duties included unloading Jews from trains, collecting their possessions...