TOKYO -- Police searched the nation today for a North Korean master spy whom authorities believe masqueraded as a missing Japanese citizen and ran an espionage ring for 15 years.
A nationwide alert was broadcast for the master spy Friday after the arrest of an alleged assistant, Kim Sok Du, 49, a South Korean resident of Japan.
Tokyo police also said they have asked Interpol, the international police clearinghouse, to notify member police agencies about the master spy.
Police said a search of Kim's house uncovered code books and radio equipment. Kim, according to a report in the Yomiuri newspaper, had traveled to Pyongyang in 1979 for six months of training as a spy.
Published reports said Kim was controlled by a North Korean using the name of 'Kenzo Kozumi,' a resident of Japan's northernmost home island Hokkaido who disappeared about 1961.
Police said the spy used the name of another Japanese citizen when he first entered Japan to set up the spy ring. In 1976, he began using the name Kozumi and obtained a driver's license and passport in that name.
The Kyodo news service, quoting police sources, said Kozumi has been identified as a senior official of the North Korean secret service in charge of training and supervising North Korean agents in Japan.
Kyodo said the spy traveled in and out of Japan nine times using the false passport. The spy's real name was not released.
According to the Tokyo Metropolitan Police's public security division, there have been 42 cases, involving 65 agents, of North Korean espionage in Japan since the end of World War II.
Japan and North Korea have no diplomatic relations although unofficial relations are maintained in many areas.