The investigation into who played key roles in the leak of classified data on the Aegis defense system has been narrowed down to several senior officers of the Maritime Self-Defense Force, according to investigative sources.
The Kanagawa Prefectural Police and the MSDF police unit expect to search the homes of the officers and other related locations early this week, the sources said.
Investigators will then seek to pinpoint who was chiefly responsible for the leak and the spread among MSDF members of material containing the data, the sources said.
Among the suspects is an officer in Yokosuka, Kanagawa Prefecture, who was in charge of formulating the material. Another is an instructor at the gunnery department of an MSDF school in Etajima, Hiroshima Prefecture, because the material is believed to have been leaked via instructors at the school, they said.
The material was formulated sometime after 1998 to train senior officers who deal with the advanced air defense systems on Aegis ships.
The material is believed to have been taken from the First Service School and stored on recording media belonging to the gunnery teacher, according to the sources.
The investigators have questioned about 300 people, including personnel from the Yokosuka unit, and teachers and students at the school.
The Kanagawa Prefectural Police and the MSDF police searched the Hiroshima school May 19 on suspicion that some of its personnel may have violated the 1954 Law Concerning the Protection of Secrets for the Japan-U.S. Mutual Defense Assistance Agreement.
The MSDF police plan to question on a voluntary basis a former school instructor who is currently on duty in the Indian Ocean.