Transcript: [Suzanne] MALVEAUX: A Texas mystery solved -- at least partially. We now know Houston police are going to start using unmanned drone aircraft. But the question remains, well, for what? Stephen Dean of CNN affiliate KPRC has got an exclusive look. STEPHEN DEAN, KPRC CORRESPONDENT (voice-over): HPD [Houston Police Dept.], the federal Department of Homeland Security and other invited guests all watching to see how this drone could be used for police work in and around Houston. We tracked that drone from News Chopper 2. And that drone was able to use a high-powered camera to track us. Those cameras can actually look into people's homes or even follow them in moving cars -- which raises all sorts of new questions. HPD quickly hustled together a news conference when it realized our cameras were there for the entire secret test. Executive Assistant Chief Martha Mantabo admits that could mean covert police action. But she says it's too early to tell what else HPD will do with the aircraft. We asked, are these drones headed for ticketing speeders from the sky? MONTALVO: I'm not ruling anything out. DEAN: Back at the secret test site, police helicopter pilots claimed the entire air space was restricted and even threatened our local 2 Investigates pilot with action from the FAA if we didn't leave. But we checked with FAA several times and there never was a flight restriction. That leaves some to wonder whether the police are now ready to use terrorism fears since 911 to push the envelope further into our private lives.