Tokyo police on Tuesday dropped their case over a 2010 leak that included sensitive details about their anti-terrorism efforts because the statute of limitations for filing charges expired.
After three years of investigating the leak, which they strongly believe was an inside job, the police failed to find enough evidence to identify a culprit, investigative sources said.
Nonetheless, the police planned to send related papers to prosecutors without naming a suspect and continue investigating in case a suspect abroad is identified, the sources said.
The statute is suspended during the period in which a suspect is out of the country.
The police at the time were strengthening security ahead of a series of APEC-related events.
The leak involved 114 documents that are believed to have been collected by the Tokyo division specializing in crimes committed by foreigners. Personal information on Muslims who cooperated with the police during anti-terrorism operations was also leaked.