Tokyo police on Tuesday turned over to prosecutors their case against a 15-year-old high school student suspected of hacking into some 140 Web sites in 23 countries and regions and defacing them with slogans opposing the war in Iraq.

According to the cybercrime unit of the Metropolitan Police Department, the youth, who lives in Hamamatsu, Shizuoka Prefecture, hacked into the Web sites of private firms, government organs and educational institutions in Asia, the United States and Europe. The teen holds the dubious honor of having caused the most damage by a Japan-based hacker, they said.

According to investigators, the teen said he began studying hacking techniques when he was in the second year of junior high school because he admired computer hackers.