Connecticut attorney general Richard Blumenthal's office will lead a multi-state investigation into Google's interception of data sent over up to 30 other US states.
The probe will decide whether privacy laws were broken by Google's fleet of Street View vehicles. The cars soaked up hundreds of GB worth of unencrypted Wi-Fi data while recording images for the mapping service in 33 countries over a three-year period.
"My office will lead a multi-state investigation expected to involve a significant number of states into Google's deeply disturbing invasion of personal privacy," Blumenthal said in a statement.
"Consumers have a right and a need to know what personal information which could include emails, web browsing and passwords Google may have collected, how and why."
When news of the data leak first broke back in May, Google was at pains to point out that while the total data gathered over the three years amounted to around 600GB, the information was "fragmented" and of no practical value. It offered to delete the data an option taken up by the UK, among others then belatedly agreed to requests from a number of other countries to hand the data over.
Far from being the end of the affair, Google's troubles have only increased since then.
Earlier this month Privacy International claimed the latest analysis showed Google had committed "a criminal act, commissioned with intent to breach the privacy of communications".
Then last week France's privacy watchdog reported that its own early investigations of the disks Google had handed over on request showed that the data included email account passwords and fragments of private messages.
Now the Connecticut probe looks set to further add to Google's concerns. With a total of 30 US states taking part in a recent conference to investigate ways of better safeguarding against such violations of privacy, the effort is likely to have plenty of support.
Google maintains that the code in the software which caused the cars to gather the data was "experimental" and had been included by mistake. It says no US laws were broken.
Blumenthal plans to force Google to provide a detailed explanation of exactly how and why the unauthorised collection of private data.
"We hope Google will continue to co-operate, [but] its response so far raises as many questions as it answers," Blumenthal added.
