A former senior U.S. diplomat who served in embassies across Latin America was accused of spying for Cuba’s intelligence service for decades in one of the highest-reaching and longest-lasting security breaches of the U.S. government, according to a criminal complaint unsealed Monday.

Victor Manuel Rocha, a former U.S. ambassador to Bolivia, was arrested by the Federal Bureau of Investigation on Friday. The unsealed complaint said that the 73-year-old Rocha had worked for Cuba’s communist government as a covert agent since at least the early 1980s until now.