A chilling documentary for which Holocaust survivor Henryk Mandelbaum returned to Auschwitz to talk about the horrific year he spent as a ‘‘Sonderkommando’’, a slave labourer forced to search and burn the corpses of fellow Jews murdered in the gas chambers. Until his death in 2008, Mandelbaum was one of very few Sonderkommando to have survived the death camps, execution as collaborators by the Soviets and later reprisals by other Jews. The stories he tells and the photographs used are stomach-churning.