For the past year, Baltimore police have secretly conducted aerial surveillance of a 30-square-mile area of the city, using technology that was employed by the U.S. military during the “surge” in the Iraq War. Ohio-based Persistent Surveillance Systems uses a small plane with high-resolution cameras to track crimes from theft to murder and save images and footage on hard drives for months. The project was funded by a private donor: John Arnold, a former Enron trader and philanthropist in Texas, Bloomberg News reported. The city of Baltimore never publicly disclosed the program’s existence. Jay Stanley, a senior policy analyst and privacy expert with the ACLU, said, “I said to myself, ‘This is where the rubber hits the road. The technology has finally arrived, and Big Brother, which everyone has always talked about, is finally here.’” The system has been in use since the beginning of the year, and has been deployed to track potential unrest during the trials of the Baltimore officers charged in the death of Freddie Gray, who was fatally injured in police custody in 2015.