The ''Holocaust'' is often characterized as the greatest crime in the history of mankind. Yet for 44 years not a single forensic investigation into this alleged crime was ever undertaken. This changed in 1988, when Fred A. Leuchter, the American expert for execution technologies, was asked by German-Canadian Ernst Zündel to go to Poland and investigate the facilities in the Auschwitz, Birkenau, and Majdanek camps, which are claimed to have served as chemical slaughterhouses for hundreds of thousands of victims – also called ''gas chambers.'' Leuchter changed the course of history when he concluded in his report: ''There were no execution gas chambers at any of these locations.'' Subsequently, Fred Leuchter also went to other camps, where mass murder with poison gas is claimed to have happened (Dachau, Mauthausen, Hartheim). He then wrote a similarly devastating report, which concluded ''that there were no gas execution chambers at any of these locations.'' This study was accompanied by an annotated bibliography about the claims regarding these three alleged locations of mass murder compiled by Dr. Faurisson. In a third expert report, Fred Leuchter described in detail the technique of execution gas chambers as used in the U.S. for capital punishment and juxtaposed it with claims about alleged Third Reich gassings. In a fourth report, Leuchter criticized a book on ''gas chambers'' written by French scholar J.-C. Pressac. This edition publishes all these reports in one volume and subjects the first of them, which has caused a huge controversy and triggered a landslide of new research, to a thorough critique, backing up Leuchter’s claims with more information and references, where he is right, and correcting him, where he erred.