Ursula Stern was an inmate of the Sobibór Camp. According to a deposition summarized and published by the Dutch Red Cross, Stern claimed that there was one gas chamber at this camp into which the gas was fed through showerheads. After the murder, the floors opened, and the bodies were discharged into a space below.
Her claims are rejected as false by the orthodoxy, who insists on several gas chambers, into which engine-exhaust gas was fed through pipes rather than showerheads. These chambers did not have collapsible floors either. The corpses were instead taken out of the chamber manually, sideways through a normal door.