Illinois Attorney General Lisa Madigan is joining other authorities around the world to investigate Google over privacy concerns with the search engine's mapping feature.
Madigan says since 2007 the search engine gathered personal information from Illinois residents while gathering data for Google's Street View service.
The service provides pictures of neighborhoods. Authorities fear the information may violate privacy laws.
Last month, Google acknowledged it had mistakenly collected data over public Wi-Fi networks in more than 30 countries. Google has also said it did nothing illegal and is working with authorities over their concerns.
Attorneys general in Missouri, Connecticut and Massachusetts, as well as authorities in Germany and Australia, are also investigating separately.