Princeton N. Lyman is the United States Special Envoy for Sudan. Prior to his appointment to the post on March 31 by President Barack Obama, he served as director of the U.S. team for north–south negotiations in the special envoy’s office. During his long career at the U.S. State Department, he served as ambassador to Nigeria and to South Africa, as assistant secretary of state for international organization affairs, and as deputy assistant secretary of state for African affairs.