Former Argentine navy officer Ricardo Miguel Cavallo (L) is escorted by Argentine policemen after his arrival at Buenos Aires International airport, March 31, 2008. Spain extradited a former Argentine naval officer to his native country on Monday to face charges of crimes against humanity during the country's "Dirty War", the Spanish Interior Ministry said. Ricardo Miguel Cavallo, once code-named "Serpico", had been held in a Spanish jail since 2003, when he was extradited from Mexico to face charges in Spain of genocide and terrorism during the 1976-83 military dictatorship in Argentina. REUTERS/Enrique Marcarian (ARGENTINA)