Police raided Google's South Korean offices today as part of their probe into the firm's Street View Wi-Fi data harvesting operation.
The country is one of many running criminal investigations into the practice, which was revealed in June.
"[We] have been investigating Google Korea on suspicion of unauthorised collection and storage of data on unspecified Internet users from wi-fi networks," the Korean National Police Agency said.
Investigators seized hard drives and documents following a search lasting several hours and involving 16 officers, the Korean news agency Yonhap reported. They also plan to summon Google executives for questioning.
Google has insisted throughout the controversy that its Street View fleet intercepted and stored payload data from unencrypted Wi-Fi networks accidentally. It came to light when European privacy authorities examined data the firm said it had collected to improve its mobile location-based services.
Today it said it will cooperate fully with the South Korean police.
The aggressive investigation so far contrasts with the approach taken by UK authorities.
The Information Commissioner's Office, responsible for enforcing the Data Protection Act, said it was satisfied on the basis of samples it had been shown by Google that no personally identifiable information had been harvested in the UK.
The Metropolitan Police meanwhile in June said it would consider a complaint by Privacy International that Google had committed a criminal offence under the Regulation of Investigatory Powers Act, which controls interception. The Met told The Register today it is still considering whether to launch a formal investigation. ®