The next step taken by Weltz, which led to the completion of the plans to conduct the high-altitude experiments on human beings at the Dachau concentration camp, was his invitation to the defendants Ruff and Romberg to collaborate with Rascher. These two men were experts in this field and were interested in further research in altitudes exceeding 12,000 meters. Weltz testified that he made a trip to Berlin and that Ruff accepted his invitation to collaborate with Rascher. (_Tr. p. 7188._) The evidence shows that Weltz approached Ruff and Romberg as he needed expert assistance. (_NO-437, Pros. Ex. 42_; _NO-263, Pros. Ex. 47_; _NO-191, Pros. Ex. 43_.) The defendant Ruff stated that he first heard of the plan to carry out research on inmates of the Dachau concentration camp from the defendant Weltz and that Weltz desired collaboration between Romberg and Rascher and between Weltz’ Institute and Ruff’s Institute. (_Tr. p. 6653._) Furthermore, Ruff testified that Weltz stated: “It is, of course, best if you or Romberg take part in these experiments because Romberg had already carried out such parachute descent experiments and is therefore the man who knows about the whole problem of rescue from high altitudes.” (_Tr. pp. 6654-5._) Ruff further testified that Weltz suggested that a new series of experiments in parachute descents from great heights should be carried out at Dachau on prisoners. (_Tr. p. 6653._) From this moment on, the experimental program started to move as a mutual undertaking. This is better stated by the defendant Weltz: “This was to be a mutual undertaking, during which Ruff was to detail Romberg and I was to detail Rascher. Ruff naturally was to be chief of Romberg and I, as a matter of course, was to be Rascher’s chief. Ruff couldn’t give any orders to Rascher. Rascher was a captain in the Medical Corps and Ruff was a civilian. I couldn’t give any orders to Romberg because Romberg was a civilian while I was a soldier. Naturally, this is how the distribution was. It had to be that way. Furthermore, it was clear that I couldn’t in any way retire. I could not just leave Rascher to Ruff. It was quite clear that I had to participate in these experiments by exercising supervision, but not by actively participating.” (_Tr. p. 7079._) This evidence certainly rebuts Weltz’ vague contention that he was not in search of specialists in high-altitude research to collaborate with him and Rascher. Without the efforts of Weltz the experiments could never have taken place. In brief, to conduct these experiments at altitudes exceeding 12,000 meters Weltz found it necessary to secure the assistance of experts in the field, as well as a low-pressure chamber which would meet his needs. Ruff and Romberg possessed both, and in the above manner Weltz skillfully engineered the whole plan.