A former staff photographer for Reuters, Dematteis has published two books: Nicaragua: A Decade of Revolution (W.W. Norton), an anthology of the Sandinista years in Nicaragua, and A Portrait of Viet Nam (W.W. Norton), which documents the social and economic transformation of contemporary Vietnam. He has exhibited extensively in the United States and abroad. Dematteis was based in Nicaragua during the war between the Sandinistas and the Contras. In 1986, his photograph of captured U.S. soldier-of-fortune Eugene Hasenfus being led through the jungle by a Sandinista soldier was named one of the top pictures of the year by The New York Times, National Press Photographers Association, and World Press Photo.
In the 1990's, Dematteis spent several years traveling to and documenting contemp-orary Vietnam, during a time when that country was opening up to the world after a long period of isolation following the end of the Vietnam War. Forging bonds with local photographers, in 1992 he directed and participated in the first exhibit by U.S. photogra-phers in Vietnam since the end of the war and in 1994 he presented the first exhibit of Vietnamese photographers to be shown in the U.S. as well. His book A Portrait of Viet Nam is a look at contemporary Vietnam and was published by W.W. Norton in 1996.
Dematteis first photographed in Ecuador in 1988. In 1993, he traveled to the Ecuadorian Amazon to document the damaging effects of Texaco's oil exploitation and resultant environmental pollution. He has returned several times to continue this documentation and has most recently focused on the heath impacts on the people of the Amazon as a result of Texaco's toxic contamination. His work from Ecuador can be seen in the exhibit Crude Reflections: ChevronTexaco's Rainforest Legacy and online at www.chevrontoxico.com. He is currently working on a book on the subject.