The Naval Criminal Investigative Service (NCIS) is the federal law enforcement agency charged with conducting investigations of felony-level offenses affecting the Navy and Marine Corps – that is, crimes punishable by confinement for more than one year. NCIS also performs investigations and operations aimed at identifying and neutralizing foreign intelligence, international terrorist, and cyber threats to the Department of the Navy. In addition, it provides warning of threats and specialized defensive force protection support to U.S. naval forces around the world.
(From: http://www.ncis.navy.mil/AboutNCIS/Pages/default.aspx)
The Archaeologist was a Spy by 
Betrayal from the East, the Inside Story of Japanese Spies in America by 
A Century of United States Naval Intelligence by 
The Naval Criminal Investigative Service : To Protect and Serve by 
