Other estimates by even jewish sources don't even come close to the figure of a loss of 6 million. What of the gas chambers? Zyklon B certainly existed, and was used, though it is an insecticide for lice and not meant for mass extermination of humans. It was claimed that at first, the Majdanek camp used "carbon monoxide", when later Zyklon B was introduced. Both carbon monoxide and cyanide poisoning produce the "red livor mortis" effect on the human body.