Belle Mayer trained as a lawyer and worked for the General Counsel of the US Treasury, Foreign Funds Control Bureau. This bureau worked to enforce the Trading With the Enemy Act passed by Congress. In this capacity, Mayer became familiar with the German I. G. Farben chemical company, a large conglomerate that used slave labor during World War II. In 1945, Mayer was sent as a Department of Treasury representative to the postwar London Conference. She was present as representatives from the Allied nations outlined the principles of law for the prosecution and trial of Europe's major war criminals. Mayer reported to this commission as it prepared for upcoming war crimes trials. She was then among the attorneys (including her future husband William Zeck) who prepared the indictment against the I. G. Farben company at the Nuremberg trials.
Our typewriters were antiquated, making carbon copies, 25 of every single thing that was done, was just backbreaking. And so we had trial lawyers who just would not stay because they could not operate in this very frustrating milieu. Interviewer: What else can you tell me about preparing for the trials themselves, the collection of evidence, who helped you in that endeavor? Belle: Well, we had analysts, translators, and we would tell them what we were looking for. I had done a draft of a trial memorandum but I'm wondering how many people on the trial team was following it very rigidly, because frequently we would send off an analyst, say to Berlin Document Center because we felt that certain points we were going to make, needed some bolstering. And they would go to Berlin and these people did work, but they would decide what they wanted to prove and they would come back with documents which they considered really incriminatory, but they were not the documents you sent them for. There were analysts, there were stenographers, there were people to whom one gave documents already in one's possession and asked them to give you a digest of them. So this was the staff, there were lawyers, analysts, stenographers, and then these kind of separate omnibus groups, like the mimeograph people.