The UK's Metropolitan Police is to investigate Google over its capture of data from unsecured wi-fi networks, following a complaint from human rights group Privacy International.
The data, scooped up by Google's Street View cars, may put the firm in breach of the Regulation of Investigatory Powers Act (Ripa).
It is likely that the police will interview Google staff in the UK.
It is one of many ongoing global investigations into Google.
Police say the initial investigation will take around 10 days, after which it will be passed to a specialist team if it is established that Google was in breach of Ripa or the Wireless Telegraphy Act.
The firm has admitted it collected data from unsecured wi-fi networks, although it said this was accidental.
The data was captured by Google's Street View cars as a result of code, designed by an engineer for a separate project, being accidentally incorporated into the system.
It captured data in 30 countries, many of which are now investigating Google. France and Germany have demanded to see the data that was collected to determine exactly what was stored.
In the US, Connecticut's Attorney General is leading a 30-state investigation and has demanded Google "come clean" about how the code came to be incorporated in its Street View system.
Google ordered an independent audit of the code, which revealed unencrypted data had been written to hard drives.
Simon Davies, director of Privacy International, welcomed the police investigation.
"An evidence-based approach to this complex matter is sorely needed now," he said.
"We hope that this difficult process will give Google pause for thought about how it conducts itself. Perhaps in future the company will rely less on PR spin and more on good governance and reliable product oversight," he added.
Google said that it is co-operating fully with all investigations and has apologised for the error.
In a blog post it said that it was "quite simply a mistake."
"The engineering team at Google works hard to earn your trust, and we are acutely aware that we failed badly here," the blog read.