The Techniques of Holocaust Denial: The Forensic Reports

Writer: Richard Green

This page is an overview of the “forensic” reports of Leuchter and Rudolf that supposedly prove that homicide by exposure to hydrogen cyanide from Zyklon-B could not have been used for mass murder in the gas chambers of the Auschwitz-Birkenau complex.

The following links lead to more in depth discussion of these “forensic” reports.

  • The Leuchter FAQ analyzes the claims of the Leuchter Report in more detail.
  • Markiewicz, Gubala, and Labedz of the Institute of Forensic Research in Crakow, Poland have published a true forensic report entitled, “A Study of the Cyanide Compounds Content in the Walls of the Gas Chambers in the Former Auschwitz and Birkenau Concentration Camps” which demolishes the claims of the Leuchter and Rudolf reports.
  • The essay Leuchter, Rudolf, and the Iron Blues addresses the chemistry of the central weakness of the the Leuchter and Rudolf reports.
  • The second part of the cyanide FAQ discusses Prussian blue and its rate of formation.
  • The Hydrogen Cyanide FAQ discusses Hydrogen Cyanide and its toxicity.

Forensic investigations of Auschwitz-Birkenau as early as 1945 found criminal traces of the mass extermination that took place there. [1]

Such criminal traces and extensive eye-witness testimony [2], [3]notwithstanding, Leuchter, Rudolf and other Holocaust-deniers claim that mass homicide by exposure to hydrogen cyanide (HCN) from Zyklon-B could not have occurred in the gas chambers of Auschwitz-Birkenau.

The deniers use two lines of arguments in their claims.

  1. They claim that there are not measureable traces of cyanide remaining in the gas chambers.
  2. They claim that homicidal gassing with Zyklon-B would have been physically impossible.

Both claims are false.

In support of the first claim they cite reports of Rudolf and Leuchter who measured higher quantities of cyanide in the blue stains of the delousing chambers than they find in the homicidal gas chambers.

In order Markiewicz, Gubala, and Labedz[4]made measurements of their own. They found traces of cyanide in the homicidal chambers at significant levels compared to other buildings at the Auschwitz-Birkenau sight. They write:

The present study shows that in spite of the passage of a considerable period of time (over 45 years) in the walls of the facilities which once were in contact with hydrogen cyanide the vestigial amounts of the combinations of this constituent of Zyklon B have been preserved. This is also true of the ruins of the former gas chambers. The cyanide compounds occur in the building materials only locally, in the places where the conditions arose for their formation and persistence for such a long time.

In their misrepresentations of this report the Holocaust-deniers will often quote the following sentence:

As far as the ruins are concerned, the presence of cyanide was demonstrated in Crematorium Chamber No. II at Birkenau.

neglecting to meantion that this sentence refers only to a preliminary study done in 1990. After they became aware of the Leuchter Report, the authors undertook a more detailed study. The results are displayed in several table ins the paper and utterly demolish the cliams of Leuchter and Rudolf.

The deniers point out that Leuchter and Rudolf measured much higher concentrations of cyanides in the blue-stained delousing chambers than in the homicidal gassing chambers. That the deniers should measure more cyanides in samples containing the blue-staining is not surprising, assuming the blue-staining is indeed composed of iron blue compounds such as “Prussian blue” as claimed by Leuchter and Rudolf. Markiewicz et. al., were careful to discriminate against such iron blue compounds in theri comparisons of cyanide levels. The reason, quite simply, is that the origin of the blue-staining is not well understood and there is no reason to assume that the formation of such compounds necessarily results whenever building materials are exposed to HCN.

To make their case that homicidal gassing using Zyklon-B was impossible the deniers rely on a few tactics. Deniers point out, correctly, that hydrogen cyanide (HCN) is a liquid a room temperature. They neglect to mention that the equilibrium vapor pressure of this liquid even at temperatures below 0 C is orders of magnitude greater than its lethal concentration. 300 ppm of HCN is rapidly fatal. The following table[5] shows the equilibrium vapor pressure of HCN as a function of temperature:

Table I
Vapor Pressure of HCN
° CTorr
(760 Torr = 1 atm)
(parts per million by volume)

When this ruse is seen through the deniers argue that HCN will not evaporate fast enough from Zyklon-B to lead to a lethal pressure within a reasonable time frame. G. Peters has established otherwise, even at low temperatures.[6]

Alternatively, deniers claim that HCN is too dangerous and that the SS were not sophisticated enough to use it safely or that it would take too long to ventilate the chamber. While there is indeed risk to the operators of the gas chambers if not done carefully, several points should be noted. The Sonderkommandos who operated the gas chambers were prisoners and the margin of safety with which the SS needed to work within was by no means equivalent to modern US OSHA standards; the underground chambers had forced ventilation; and the Sonderkommandos sometimes had gas masks. Pressac[7] describes a gassing that took place March 13, 1943:

That same night, 1,492 women, children, and old people, selected from a convoy of 2,000 Jews from the Krakow ghetto, were killed in the new crematorium.133 Six kilos of Zyklon B were poured into the stacks that opened into the four grillework columns implanted between the pillars that supported the ceiling.133 Within five minutes, all the victims had succumbed. The aeration (8,000 cu m an hour) and deaeration system (same strength) were then started up and, after 15 to 20 minutes, the atmosphere, which had been practically renewed every three to four minutes, was sufficiently pure so that members of the Sonderkommando could enter the stiflingly hot gas chamber. During this first gassing [in the new Krema II gas chamber-my note RJG], the Sonderkommandos wore gas masks as a precaution. The bodies were untangled and dragged to the goods elevator. Hair was clipped, gold teeth pulled out, wedding rings and jewels removed.

Perhaps, the only remaining question is whether deniers who are aware of the evidence against their claims actually believe their own arguments or whether they are perfectly aware of the insufficiency of their own claims.