"there was talk of the Sonderkommando, the Special Kommando attached to the gas chambers and the ovens"
Sonderkommando at Birkenau
Public DomainSonderkommando at Birkenau

The Sonderkommando (Special Command Units) were Jewish prisoners forced to work in the industrial murder of their fellows. Their duties included guiding the new arrivals into the gas chambers, removing the bodies afterwards, shaving hair, extracting teeth, sorting through possessions, cremating the bodies in the crematoria or open air pits, and disposing of the ashes. Sonderkommando members did not participate directly in killing; that responsibility was reserved for the guards. Their primary responsibility was the disposal of corpses.

The Sonderkommando were inducted immediately upon arrival at the camp, and were not given any advance notice of the tasks they would have to perform. They had no way to refuse or resign other than by committing suicide. Sonderkommando members tended to survive longer than other inmates of the death camps—but very few survived the war.