More than 30 US states have kicked off a probe into Google's Street View data collection practices.
The states will investigate whether the search company violated citizens' privacy when the cars collecting images for the Street View service accessed local Wi-Fi networks.
Connecticut attorney general Richard Blumenthal, who is leading the probe, said that his office will look at the extent to which Google accessed the Wi-Fi networks, and examine the firm's internal policies concerning data collection and network security.
"Google needs to describe how code that intercepted and collected unencrypted data transmitted over Wi-Fi networks was inserted into its software," he said. "We want to know who did this, why and how, and when Google discovered it."
Blumenthal also maintained that Google should be doing more to co-operate with investigators.
"While we hope Google will continue to co-operate, its response so far raises as many questions as it answers," he said.
"The company must provide a complete and comprehensive explanation of how this unauthorised data collection happened, why the information was kept if collection was inadvertent and what action will prevent a recurrence."
Google is already under investigation by government bodies in Europe which have sought to determine the extent to which the company had harvested data.
Google has insisted that the Wi-Fi data collection was a "mistake", and has offered to hand over the information to European authorities.
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