The Philadelphia Police Department has begun an investigation into why officers disguised an SUV to look like a Google street mapping vehicle and equipped it with license-plate-reader cameras, reports Motherboard.

The vehicle was discovered by Matt Blaze, a University of Pennsylvania computer and information science professor. Blaze tweeted a photo of the vehicle and found a placard showing it was registered to the city's Office of Fleet Management. The city's fleet manager told the outlet he believes it's being used for law enforcement activity.

A Google spokeswoman declined to comment on the matter.