The doohickey seems to stare at you. Two wide eyes set in an all but indestructible black box, the Mobile Plate Hunter-900 is D.C.’s own panopticon. At a hefty cost of $16,000 to $20,000 per device, the unblinking Metropolitan Police Department robot never misses a thing. It steals a color image with one lens and an infrared one with the other. That’s how it spotted 18 year-old Deandrew Hamlin.

Just hours after one of the devices was installed somewhere in the area of Benning Road NE last week, the technology may have proven its worth. MPD spokesperson Istmania Bonilla told The Washington Post that as a Jeep Cherokee rolled by on Oct. 25, the device did what it was made to. It scanned the vehicle’s tags, and began comparing the numbers against a “hot list” of stolen vehicles. It got a ping.

Alerted by the machine, cops chased down Hamlin, an alleged car thief and a murder suspect. Cops say Hamlin was driving the car of slain American University professor Sue Ann Marcum, 52.

But if that’s the correct version of events, police charging documents don’t make that clear. In an affidavit regarding Hamlin’s arrest, officer W. Dempster makes no mention of the License Plate Recognition (LPR) contraption cops have been phasing in since about 2005, tipping him off.

I, Officer Dempster was on duty as”Auto Theft 69″in the area of the 2400 block of Benning Road, NE Wash, DC. There I observed a gold in color Jeep Cherokee SUV bearing Virginia tags YXEl456 traveling west bound on Benning Road, Northeast. I saw that the Jeep was occupied only by the driver and I recognized it matched a look out for a felony vehicle wanted in connection to a Montgomery county homicide from earlier in the day.

Nate Maloney, a spokesperson for the technology company that sells Mobile Plate Hunters to MPD, says they installed four of their machines in the District the day Hamlin was caught, and that one of them was definitely on Benning Road. Though many of the machines are attached to police cars, that particular one is a stand-alone, he says. Maloney wasn’t surprised when he read that his machines had helped tracked down a stolen car.

Though cops run tags all the time, one advantage the computerized tag hunters have is they don’t carry around prejudices: “It’s an equal opportunity profiler, if you will,” says Maloney. The machine takes note of every single vehicle it encounters, including those that are parked.

Uninfluenced by the kind of  subconscious stereotyping that makes taking the Harvard race test a frightful experience, the machine is perhaps a useful addition to a police department that in 2006, discovered it was keen on stopping black and Latino pedestrians in Georgetown and Adams Morgan.

A police department source who works on fighting auto theft in the District says the machines have done more than remain colorblind, though; they’ve also been wicked efficient, helping to recover stolen vehicles faster than humanoid cops can. “It’s impossible to go down the street and run every tag,” he admits.

But as more and more patrol cars and neighborhoods are rigged with the machines, there would seem to be at least two concerns: The price tag, which gets worse when you consider warranty costs that run about $1,500 a year for each unit, and privacy. Though for now, MPD mostly uses their mechanical snoops to look for stolen cars (and perhaps terror suspects), the device can be tweaked to ping for other reasons, and that worries the American Civil Liberties Union.

“ALPRs raise serious concerns to your privacy because of the system’s ability to monitor and track the movements of ALL vehicles,” reads a blog post on the ACLU website, “including those registered to people who are not suspected of any crime.”

The civil rights lawyers could be onto something. A police source says MPD has used images from the devices to figure out what cars were in the area of a crime scene in the moments when patrol cars arrived. So you could end up being scrutinized  simply because your vehicle was in the wrong place at the wrong time.

That’s the down side of a surveillance device with indiscriminate ways—the paranoid among us have little chance of staying completely clear of it. Still, if cops are expected to deliver on making D.C. streets as safe as concerned residents seem to want them to, it’s likely to cost something even more precious than tax dollars—like the ability to stay off the grid.

So did the machine locate Hamlin or what? Contacted, Bonilla says she hasn’t heard anything to the contrary.  Seeing that would-be terrorist Metro attacks and mail bombs have shown up in the news cycle of late, that’s a win for a surveillance culture we’re likely to see more of.