Numerous witnesses have claimed to have been present when an alleged homicidal gas chamber at a German wartime camp was opened after a mass execution using poison gas. Many of them have described that the packing density of the victims inside the gas chamber was so high that there was no room for the dead victims to fall over, so most or all of them kept standing upright even after death.
The frequently claimed packing densities of ten persons per square meter and more are not only unlikely or even impossible, but they could also not explain why the dead would keep standing upright. Even if the upper bodies of people squeezed into a room are packed tightly together – an act that requires discipline and voluntary cooperation – there is enough room for the legs to fold, hence for the bodies to slump down and tilt any which way. Note also that the human body does not go stiff from inhaling hydrogen cyanide (the active ingredient in Zyklon B) or carbon monoxide (the most-lethal component of engine-exhaust gasses). Furthermore, it takes hours for rigor mortis to set in, meaning the stiffening of muscles after death. Therefore, the tale of people standing upright in their death is a myth.
Here is a list of witnesses who have made statements to this effect, displaying a “convergence of evidence” on a lie: