Complex sentence: Marciel has worked for the United States Department of State since 1985 and served in various capacities abroad and in particular was the United States Ambassador to the Association of Southeast Asian Nations prior to his nomination in Indonesia.
Split into simpler sentences: Marciel has worked for the United States Department of State since 1985. He has served in various capacities abroad and in particular was the United States Ambassador to the Association of Southeast Asian Nations prior to his nomination in Indonesia.