Complex sentence: Following his tour of duty, he became a Baton Rouge police officer and also worked with the U.S. State Department's Anti-Terrorism Assistance Program instructing police officers from other countries.
Split into simpler sentences: Following his tour of duty, he entered the law enforcement arena, working for the Baton Rouge municipal police. During this time, he also worked with the U.S. State Department's Anti-Terrorism Assistance Program and instructed police officers from other countries.