In 1985, she became an assistant United States Attorney. In 1998, President Bill Clinton appointed her the US Attorney for the Western District of New York. While working for the US Attorney's office she worked on two particularly prominent cases. The first was the investigation into Oklahoma City bomber, Timothy McVeigh. She was also the leader in the successful prosecution of anti-abortion extremist James Kopp for the murder of obstratician and abortion provider Barnett Slepian. She was pushed out of her position as US attorney by the Bush administration before her term had ended.