On a Wednesday morning in mid-July, I stared at a parking spot, hoping that if I looked hard enough, the car that I had planned to move from one side of the street to the other would appear. When it didn’t, I walked to the 3rd District police station and reported the ’96 Volkswagen, with faded red paint and two bullet holes, stolen. And that, I assumed, was that.

On the following Friday evening, an officer called to say that the car had been recovered. He told me that it was found by using a device that electronically scans license plates and runs the number through a database, looking for irregularities.

The two men caught in the VW, both homeless, were most likely unaware of the technical prowess they were up against while driving along the 1700 block of 2nd Street NW. The tag reader zapped them and they were pulled over.

“They were in shock,” said arresting officer Brian Wymbs.

Indeed, it appeared the new owners had no plans to dump the car. The thieves had filled up the tank and added oil. A half-empty bottle of STP was found in the trunk. (The engine now runs noticeably more smoothly.) In addition to the engine treatment, two 5-gallon plastic buckets, an orange construction vest, an empty 24-ounce Icehouse can, a computer printer, and a flier for an upcoming church function were left in the car.

With technology that represents a breakthrough in catching car thieves, you’d think D.C. police would be hyping their new gadget left and right. But you won’t find any press releases about the machine. Hell, you’ll have a hard time getting the cop who recovered your car to talk about it.

In that initial phone call, the officer told me that the device had not been disclosed to the general public. Told that he had just disclosed it to a reporter, he referred further questions to the auto-theft unit.

When contacted about the plate hunter, Sgt. James Manning of the auto-theft unit replied in an e-mail that the department “has never spoken publicly about this technology.” He wouldn’t elaborate, other than to say that the cats gain a tactical advantage over their prey by secreting the weapon away. “It’s a methods-and-sources issue,” he said.

The cops have been shady about the tag reader with civilians, too. One officer who uses the device (and declined to be identified to avoid getting in trouble with his bosses) says that he and others are dodgy when asked about the contraption on their cruisers. “People say, ‘What’s that on top of your car?’ We tell ’em it’s checking the air or whatever. Whatever they think it is, that’s what we tell them,” he says.

The justification for such secrecy, the cops say, is that evildoers are easier to catch while actually driving the stolen vehicle, ignorant of the new technological advantage. Hence more lockups and, in theory, fewer car thieves on the street.

The tag reader, which sells for around $20,000, was developed by an Italian postal-technology company, Elsag. It grew out of a machine the Italian postal service used that could scan postcard addresses and sort them for delivery. It’s now marketed as the Mobile Plate Hunter 900 in partnership with gunmaker Remington. According to a Web site promoting the device, it “translates the read plate data into a digital image, checks versus an onboard hot list, and returns an alarm back to the operator in milliseconds for appropriate interdiction.”

Other departments have not been so tight-lipped. Elsag’s tag zinger was tested last year by Los Angeles County police, and similar technology has since spread to units from Mesa, Ariz., to Prince George’s County. In its first run in L.A.—as touted in a company press release—it nabbed seven stolen cars, one of them driven by a parolee in his parole officer’s parking lot. The device is mounted on top of the car; the company’s Web site says it can read up to four lanes of traffic at a passing speed of more than 75 mph. At 60 mph, it can read an oncoming car’s plate that is going 60 or slower. The company says it scans between 500 and 800 plates an hour.

Over at the Department of Public Works, no one seems to care much about the implications of revealing the technology. The agency is happy to let me ride along with one of its five plate hunters on a recent Tuesday afternoon. As Edwin Pacheco and Larry Worrell cruise onto 18th Street NW from Belmont Road, a buzz that sounds as if it belongs in a video game causes Pacheco to hit the brakes. A beige Mercedes-Benz E320 that owes $220 in back tickets has earned itself a boot, but because it’s in a rush-hour lane, it’s spared this time around.

Worrell, who was booted himself about seven years ago, looks pissed. “That’a been a nice hit, but we can’t mess with it. If it’d been on a side street we could’ve got it,” he says.

By this point, the van, with two cameras mounted on the roof and two off the back, has been on the road for four-and-a-half hours and has scanned 4,177 plates. Pacheco pulls off down 18th; the van’s moving at about 30 mph and scanning plates on both sides of the street. On the 1700 block of Vermont Avenue NW, the scanner hits on a gray Chevy Aveo with Maryland tags whose owner owes $195; Pacheco stops, and Worrell has it booted in under a minute. A green Isuzu Rodeo at the end of the block suffers the same fate.

Worrell and Pacheco say they’ve heard that the police department is using the same technology, but the DPW machines are only set up to catch parking scofflaws. Their database can’t catch car thieves or even speeding-ticket deadbeats.

But getting caught by one of the cops’ auto-theft scanners doesn’t necessarily mean a direct trip to prison. When the VW was spotted on July 14, it was still sporting its original tags as Wymbs and his partner pulled behind it. The driver and passenger were arrested and booked; the charges were forwarded to the U.S. Attorney’s Office for prosecution—just the sort of case the tag reader was intended to bring.

But prosecutors weren’t having it. The office initially decided to “no paper” the case—not pursue the charges—because the men somehow had a key for the car. Prosecutors like to avoid “key cases,” says office spokesperson Channing Phillips, because the defendant can claim he borrowed the car—from the owner, from anyone—and had no idea it was stolen.

Worrell doesn’t think there’s much reason for the cops to keep the plate scanners secret. “There’s not really too much [car thieves] can do about it. Nine times out of 10, they don’t care if a cop is running their plate. They’ll just go steal another one,” he says.CP