When the British analyzed the Enigma Code, they were able to intercept the daily reports given by the camps. Total numbers in the camps. People in, people out, number of deaths and cause of death were reported. By far the biggest cause of death reported was disease but they also mentioned shootings and executions. The thing that was never reported is what is usually sold as the main method of the killings; gassing...

“ The messages from Auschwitz, the largest camp, with 20,000 inmates,[4] mention disease as the chief cause of death, but also include references to executions by hanging and shooting. The decoded messages contain no references to gassings."

• Francis H. Hinsley - British Intelligence in the Second World War.