Letter from Dr. August Becker, SS Untersturmführer to SS-Obersturmbannführer Rauff, 16 May 1942 in Nazi Conspiracy and Aggression - Washington, U.S Govt. Print. Off., 1946, Vol I, p. 999-1000:
The overhauling of vans by groups D and C is finished. While the vans of the first series can also be put into action if the weather is not too bad, the vans of the second series (Saurer) stop completely in rainy weather. If it has rained for instance for only one half hour, the van cannot be used because it simply skids away. It can only be used in absolutely dry weather. It is only a question now whether the van can only be used standing at the place of execution. First the van has to be brought to that place, which is possible only in good weather. The place of execution is usually 10 to 15 km away from the highways and is difficult of access because of its location; in damp or wet weather it is not accessible at all. If persons to be executed are driven or led to that place, then they realize immediately what is going on and get restless, which is to be avoided as far as possible. There is only one way left; to load them at the collecting point and to drive them to the spot.
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 larger 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.
Because of the rough terrain and the indescribable road and highway conditions the caulkings and rivets loosen in the course of time. I was asked if in such cases the vans should be brought to Berlin for repair. Transportation to Berlin would be much too expensive and would demand too much fuel. In order to save those expenses I ordered them to have smaller leaks soldered and if that should no longer be possible, to notify Berlin immediately by radio, that Pol.Nr. is out of order. 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 the commanders of those S.K. concerned the immense psychological injuries and damages to their health which that 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 those damages, I request orders be issued accordingly.
The application of gas usually 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 now have 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.
Today I shall continue my journey to group B, where I can be reached with further news.
Signed: Dr. Becker, SS Untersturmführer.
Letter from Willy Just to SS-Obersturmbannführer Walter Rauff, 5 June 1942 in Nazism: A History in Documents and Eyewitness Accounts, 1919-1945. Volume II, J. Noakes and G. Pridham, editors. Schocken Books, New York, 1988 by the Dept. of History and Archeology, University of Exeter. ISBN 0-8053-0973-5 (vol. 1), 0-8052-0972-7 (vol. 2). Document #913:
RE: Technical alterations to the special vehicles already in operation and those in production.
Since December 1941, for example, 97,000 have been processed using three vans without any faults developing in the vehicles. The well-known explosion in Kulmhof (Chelmno) must be treated as a special case. It was caused by faulty practice. Special instructions have been given to the relevant offices in order to avoid such accidents. The instructions were such as to ensure a considerable increase in the degree of security.
Further operational experience hitherto indicates that the following technical alterations are appropriate....
2) The vans are normally loaded with 9-10 people per square meter. With the large Saurer special vans this is not possible because although they do not become overloaded their maneuverability is much impaired. A reduction in the load area appears desirable. It can be achieved by reducing the size of the van by c. 1 meter. The difficulty referred to cannot be overcome by reducing the size of the load. For a reduction in the numbers will necessitate a longer period of operation because the free spaces will have to be filled with CO. By contrast, a smaller load area which is completely full requires a much sorter period of operation since there are no free spaces....
3) The connecting hoses between the exhaust and the van frequently rust through because they are corroded inside by the liquids which fall on them. To prevent this the connecting piece must be moved so that the gas is fed from the top downwards. This will prevent liquids flowing in....
6) The lighting must be better protected against damage than hitherto....It has been suggested that lighting should be dispensed with since they are allegedly never used. However, experience shows that when the rear door is closed and therefore when it becomes dark, the cargo presses hard towards the door....It makes it difficult to latch the door. Furthermore, it has been observed that the noise always begins when the doors are shut presumably because of fear brought on by the darkness.
Letter from SS-Hauptsturmführer Truehe to Reich security office, room 2D3A in Nazi Conspiracy and Aggression - Washington, U.S Govt. Print. Off., 1946, Vol. I, p. 1001:
A transport of Jews, which has to be treated in a special way, arrives weekly at the office of the commandant of the Security Police and the Security Service of white Ruthenia. The three S-vans which are there are not sufficient for that purpose. I request assignment of another S-van (five tons). At the same time I request the shipment of twenty gas hoses for the three S-vans on hand since the ones on hand are leaky already.