Who is Ken McCoy from Line of Fire and what is their importance?

Ken McCoy is a Lieutenant in the Marine Corps and the older brother of Sergeant Thomas McCoy. He served in China and is known as "Killer" McCoy. He is romantically involved with Ernestine Sage, a friend of Pick and heir to a pharmaceutical fortune. He is from Pennsylvania and works as a Special Agent for the Office of Naval Intelligence. Ken heads the team involved in Operation Pickle.