The SS agreed to provide Farben with one thousand slave workers immediately. That number, promised Himmler, could quickly rise to thirty thousand with demand. The relationship between Farben and the SS at Auschwitz was now cemented. Otto Ambros was the key to making the Buna factory a success. With his knowledge of synthetic rubber and his managerial experience—he also ran Farben’s secret nerve gas production facilities—there was no better man than Otto Ambros for the Auschwitz job.
Major Tilley waited at Dustbin for the return of Tarr and Ambros. It was now clear to him that there was no single individual more important to Hitler’s chemical weapons program than Otto Ambros had been. Ambros was in charge of chemical weapons at Gendorf and Dyhernfurth, and he was the manager of the Buna factory at Auschwitz. From interviewing various Farben chemists held at Dustbin, Tilley had also learned that the gas used to murder millions of people at Auschwitz and other concentration camps, Zyklon B, was a Farben product. Farben owned the patent on Zyklon B, and it was sold to the Reich by an IG Farben company. In one of these interviews, Tilley asked IG Farben board member Baron Georg von Schnitzler if Otto Ambros knew that Farben chemicals were being used to murder people.
“You said yesterday that a [Farben employee] ‘alluded’ to you that the poisonous gasses [sic] and the chemicals manufactured by IG Farben were being used for the murder of human beings held in concentration camps,” Major Tilley reminded von Schnitzler in their interview.
“So I understood him,” von Schnitzler replied.
“Didn’t you question those employees of yours further in regard to the use of these gases?”
“They said they knew it was being used for this purpose,” von Schnitzler said.
“What did you do when he told you that IG chemicals were being used to kill, to murder people held in concentration camps?” Major Tilley asked.
“I was horrified,” said von Schnitzler.
“Did you do anything about it?”
“I kept it for [sic] me because it was too terrible,” von Schnitzler confessed. “I asked [the Farben employee] is it known to you and Ambros and other directors in Auschwitz that the gases and chemicals are being used to murder people?”
“What did he say?” asked Major Tilley.
“Yes; it is known to all the IG directors in Auschwitz,” von Schnitzler said.
For Lieutenant Colonel Philip R. Tarr, there was a mission at hand. Enemy Equipment Intelligence Service Team Number One, which he served on, needed information that only Dr. Otto Ambros had. Specifically, the team needed blueprints for equipment necessary for producing tabun nerve gas.
When Tarr and Ambros arrived in Heidelberg, the U.S. Chemical Warfare Service had another IG Farben chemist in custody whom they wanted Ambros to work with on a classified job. The man is referred to in documents only as Herr Stumpfi. Ambros and Stumpfi were told to drive to a special metals firm located in Hanau, where they were to locate “30 or 40 drawings of silver-lined equipment.” The Chemical Warfare Service trusted Ambros to such a degree that they sent him and Stumpfi on this mission without an escort.
Manufacturing tabun gas was a precise and clandestine process. The United States desperately wanted to reproduce it, but attempting to do so without Farben’s proprietary formula and its secret equipment was a potential death sentence for any chemists involved. Farben had spent millions of reichsmarks on research and development. Hundreds of concentration camp workers had died in this trial-and-error process. When the U.S. Chemical Warfare Service learned that the silver-lined equipment used to manufacture tabun gas on a large scale had been outsourced from a special metals firm called Heraus, they coveted those blueprints and plans. Dr. Ambros and Herr Stumpfi were to go to this engineering firm to locate these drawings and blueprints and bring them back to Heidelberg. The Chemical Warfare Service agents could not conduct this mission on their own because they had no idea what equipment to look for.
The two Farben chemists, Ambros and Stumpfi, set off on their secret assignment. “When they arrived at the factory in Hanau, personnel of a [U.S.] CIC [Counter Intelligence Corps] group with headquarters at that time in Hanau, arrested them,” read a secret report. “When they explained their mission the CIC personnel concerned confirmed the German engineers’ statement by communication with Heidelberg and the two Germans were released.” Ambros and Stumpfi drove away. “The CIC personnel, concerned [after] having learned of the drawings through the two German engineers, then seized the drawings and took them to their own headquarters,” read a classified Army report. The Chemical Warfare Service never obtained the drawings they were looking for. But at least Tarr had Dr. Ambros under his control, or so he believed.