Andersen previously served as the organization's vice president.

Andersen is the author of three books on Latin American issues. In 2010 he published "Peoples of the Earth; Ethnonationalism, Democracy and the Indigenous Challenge in 'Latin' America" (Lexington Books). He is also the author of "Dossier Secreto: Argentina's Desaparecidos and the Myth of the 'Dirty War" (Westview Press, 1993), which The New York Times hailed as a "tour de force." And in 2002, he published "La Policia: Pasado, Presente y Propuestas para el Futuro" (Sudamericana), a history of the Argentine police. 

Andersen holds a master's degree in international relations from the Johns Hopkins University School of Advanced International Studies (SAIS) in Washington, D.C. and Bologna, Italy, and a second master's in American history from The Catholic University of America. Currently studying for his doctorate at Catholic, Andersen is expected to graduate in 2011 after presenting his dissertation on the late Robert C. Hill, who served as U.S. ambassador to Buenos Aires in the mid-1970s.

Andersen is also the recipient of the 2001 "Public Servant Award" from the U.S. Office of Special Counsel, the first ever given to a national security whistleblower, for contributions made as a senior advisor for policy planning at the Criminal Division of the U.S. Department of Justice.