Police wiretapped mobile phones in 10 investigations last year and the eavesdropping led to the arrest of 22 people, a Justice Ministry report to the Diet showed Friday.
The 10 investigations involved narcotics trafficking, underworld-conspired murder and gun possession, three of the four areas in which courts issue wiretapping warrants. All 22 arrests involved drug-trafficking cases, according to the report.
The police obtained warrants for each instance of cellphone-tapping, allowing them to listen to conversations and read text messages.
In one case, however, the court rejected the initial request for a warrant — the first time such a request has been refused since the law on wiretapping in criminal investigations was enacted in 2000.
Police sought the warrant to wiretap two mobile phones as part of a probe into gun possession, but the court said it did not meet legal requirements.
But the court later issued the warrants after the police reopened the investigation, allowing them to listen in on mobile communications for 10 days. Ultimately, the investigation did not result in any arrests, the report said.