The 1988 report by Fred Leuchter, often called the "Leuchter Report," is frequently cited in discussions about Holocaust denial, but it has been widely discredited by historians, scientists, and legal experts. Leuchter, an American who claimed expertise in execution technologies, was hired by Holocaust denier Ernst Zündel to examine the Auschwitz camp and provide evidence against the existence of gas chambers. However, Leuchter’s methods, findings, and conclusions have been thoroughly invalidated for several reasons:

Lack of Qualifications and Expertise: Leuchter had no formal training in chemistry, toxicology, or engineering relevant to evaluating historical sites for chemical residues. He was neither a chemist nor an engineer qualified to analyze residue left by Zyklon B, the cyanide-based pesticide used by the Nazis.

Improper Sampling Methods: Leuchter’s sampling was unscientific. He chiseled samples from walls without any controlled procedures, which would contaminate the samples and make the results unreliable. The nature of cyanide residue is such that it forms a compound that can be removed or degraded by exposure to elements, which Leuchter did not account for.

Misinterpretation of Chemical Evidence: He failed to understand the chemistry of how Zyklon B residues bond to walls. Studies have shown that even if high levels of cyanide were present during the time of operation, decades of exposure to the elements, as well as the cleaning and repurposing of the structures after the war, would diminish detectable levels of the residue. This has been substantiated by more rigorous studies conducted by qualified chemists and historians, such as those by the Institute for Forensic Research in Kraków in the 1990s.

Subsequent Rebuttals by Historians and Forensic Experts: Detailed studies with proper methodologies, such as those by Jan Markiewicz and others, have demonstrated the presence of cyanide residues in gas chamber walls at Auschwitz, confirming historical evidence and eyewitness testimonies.

The report’s conclusions have been comprehensively discredited in both historical scholarship and in courts of law, where it has been deemed pseudoscientific. The persistence of references to the Leuchter Report on the internet is largely due to Holocaust denial circles and misinformation campaigns, which use it to cast doubt on historical evidence without basis in credible science or historical research.