Washington asked Burton to help the investigation of the assassination of Israeli Prime Minister Yitzhak Rabin. He used to be the deputy chief of the counter-terrorism part of the U.S. State Department's Diplomatic Security Service. He also investigated the killing of Rabbi Meir Kahane, the al Qaeda New York City bombing plots before the September 11 attacks and the Libyan-backed terrorist attacks against diplomats in Sana'a and Khartoum. He helped in the arrest of Ramzi Yousef, the mastermind of the first World Trade Center bombing in 1993.