Erbelding is initially sceptical that the photographs are as described. She is aware of all the known relatively rare photographs taken at Auschwitz. But then she recognises the man whom she had already researched at length, Josef Mengele. He is smiling among a group of Nazi officers including the camp’s final commandant Richard Baer. It is quickly established that the photos belong to Baer’s proud adjutant Karl Höcker who is present in many of the photographs. What makes these pictures extraordinary is that they are entirely of happy and relaxed Nazis during their time off from the job of processing,...