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.
Oh, there was a toll, there was a very, a very definite toll. I can't quantify it, but I had thought before I went there that I knew a great deal about the atrocities that had taken place, but it seemed to me that every day was a fresh revelation. I think that after a while, one became inured to it. I remember hearing myself say, it's hard to believe of me, but I remember one of the analysts coming to me once with a story about experiments on five people and I said something unpleasant like, "Why would you bring me a document about five people when we have documents which involve several hundred people?" Now that's a perfectly horrible kind of comment to make. When I came home from Nuremberg, shortly thereafter, a little girl fell in a well, I think it was in Texas, and this entire country held its breath until that child was retrieved. But a million little girls like that and boys were murdered by the Nazis and the fact is that the world did very little about it.