The New York Police Department already has the long arm of the law. Now it gets X-ray eyes.

NYPD Commissioner Ray Kelly says officers are in the advanced stages of testing a futuristic new weapon in their war against gun-toting residents: a device that can detect the presence of hidden metal from a distance.

The device measures terahertz, the natural energy emitted by people and objects. "If something is obstructing the flow of that , for example a weapon, the device will highlight that object," Kelly said in a speech Wednesday.

The boxy machine can be hidden in a vehicle, allowing officers to discreetly scan their target. The is being seen as a possible alternative to the NYPD's reliance on the controversial tactic of stop-and-frisk, where officers routinely search large numbers of men in high-.

"We still have a number of trials to run before we can determine how best to deploy this technology. But we're very pleased with the progress we've made over the past year," Kelly said.

(c) 2013 AFP