Belle Mayer Zeck, who died Saturday at 87, was an associate counsel at the Nuremberg trials in the wake of World War II, where she helped prepare the case against the leaders of the pharmaceutical and chemical giant I.B. Farben, which produced synthetic rubber and oil for the German war effort, as well as the killer gas Zyklon-B.

The case against Farben stretched into July 1948, and ended in a mixed verdict that allowed several of the principle defendants to become post-war German business leaders.

Belle Mayer left Germany in the middle of the case, in December 1947, due to illness. There was an unexpected positive development, however: A romance she began with another Nuremberg prosecutor, William Zeck, blossomed. The two lawyers became partners in marriage, and in a long-time legal practice in Suffern, N.Y.

Belle Mayer was raised in Suffern, the daughter of a tavern owner who fell briefly on hard times when prohibition was enacted, in 1919. He became a dairy farmer, and later bought a soda and (after 1933) a beer bottling business.

Belle Mayer majored in economics at Syracuse University, and earned at law degree at Fordham in 1940. She joined her brother’s law practice in Suffern. When he was drafted the following year, Belle Mayer moved to Washington, D.C., where she worked as an attorney in the general counsel’s office at the U.S. Treasury Department.

She first met William Zeck, a young prosecutor on Telford Taylor’s Nuremburg prosecution team, when Zeck asked her for documents related to the Farben case. She refused to provide them, and family lore has it that it was her bullheaded charm that most interested Zeck. At his suggestion, she was added to the prosecution team as the only person with the necessary familiarity with the documents in question. Her extensive research crew would come to be known on the prosecution team as “Belle’s WPA.”

At Belle Mayer’s suggestion, Taylor brought in her old boss from the treasury, Josiah DuBois, as head prosecutor in the Farben case, which finally wended its way to trial in the summer of 1947.

Having returned to America, Belle Mayer described her impression of the defendants to the Woman’s National Democratic Club in December, 1947: “They look like and act like businessmen, but they were in fact the principal advocates and planners of German military conquest. They were the boys who put mass murder on a sound industrial basis and brought all effective techniques of scientific management to the business of killing human beings.”

Of the 24 Farben employees charged with a variety of crimes including war crimes and enslavement, 10 were acquitted and seven were sentenced to more than two years in prison. The case was widely regarded as a failure, including by its chief prosecutor, Dubois, who wrote his memoir “The Devil’s Chemists” (1952) “To understand the full significance of this story, bear in mind that today the main characters – defendants in the most far-reaching criminal trial in history – are all alive and free to work against the way of life you and I cherish.”

Belle Mayer, too, was disappointed at the verdict, and in later years despaired of legislating away aggression. “I just think people are going to continue to make war, that’s all – whether it’s Haiti or Bosnia or Rwanda,” she told the Philadelphia Inquirer in 1996. “There just doesn’t seem to be any rational settlement of these ancient grudges.”

Her husband, whom she married in 1949, was more sanguine about international agreements.

The couple settled in Suffern, where they raised a family and started a law partnership with Belle Mayer’s brother. Belle Mayer was a founding trustee of Rockland Community College, and in 1960 ran unsuccessfully for state Assembly in Rockland County as a Democrat. For many years, she was the Ramapo town attorney.

William Zeck was an upstate campaign manager for Robert F. Kennedy’s campaigns for Senate and the presidency. In 1981, he became a state Supreme Court judge in White Plains.

Belle Mayer and her husband frequently addressed church and synagogue groups about their postwar work. Farben “had affiliations all over the world, and from 1936 on their salesmen were open, naked spies,” she told the Baltimore Jewish Times in 1996.

Asked about what it was like in Nuremberg in 1947, when she was making the case against war criminals and being courted by her future husband of 53 years, Belle Mayer said, “It was a terrible place. But I do remember one weekend in Prague.”

Belle Mayer Zeck

Born February 22, 1919, in Fort Henry, N.Y.; died March 18 at her home in Suffern; survived by her children, Deborah Zeck Thorne and John Gustav Zeck, and four grandchildren; her husband William Zeck died in 2002.