In February 1985 the historian David G. Marwell was working at the US Department of Justice when he was assigned to join an international search for Mengele, then believed still to be alive. Marwell already had access to Mengele’s correspondence and diaries and, remarkably, the text of what appeared to be an autobiographical novel. A note attached to it, addressed to Mengele’s son, expressed the pious hope that in time it would be possible to understand what he had done, and that there would be ‘more liberal treatment of difficult themes’. Marwell deciphered the text (much of it attempting to disguise real names and events), and it provides the basis for his book, Mengele: Unmasking the ‘Angel of Death’. It must be the most thorough-going account of Mengele’s life available to date, a calm and professional read, but one that inevitably makes you want to look away.