I ordered the vans of group D to be camouflaged as house trailers by putting one set of window shutters on each side of the small van and two on each side of the large vans, such as one often sees on farm houses in the country. The vans became so well known, that not only the authorities but also the civilian population called the van “death van”, as soon as one of these vehicles appeared. It is my opinion the van cannot be kept secret for any length of time, not even camouflaged… Besides that, I ordered that during application of gas all the men were to be kept as far away from the vans as possible, so they should not suffer damage to their health by the gas which eventually would escape.
I should like to take this opportunity to bring the following to your attention: several commands have had the unloading after the application of gas done by their own men. I brought to the attention of those S.K [Special Kommando] concerned the immense psychological injuries and damages involved to their health that this work can have for those men, even if not immediately, at least later on. The men complained to me about headaches which appeared after each unloading. Nevertheless they don’t want to change the orders, because they are afraid prisoners called for that work could use an opportune moment to flee. To protect the men from these damages, I request orders to be issued accordingly. The application of the gas is not undertaken correctly. In order to come to an end as fast as possible, the driver presses the accelerator to the fullest extent. By doing that the persons to be executed suffer death from suffocation and not death by dozing off as was planned. My directions have now proved that by correct adjustment of the levers death comes faster and the prisoners fall asleep peacefully. Distorted faces and excretions, such as could be seen before, are no longer noticed.
Nazi Conspiracy and Aggression (Washington: US Government Printing Office, 1946), Vol III, p. 418.