OAKLAND, Calif. — The purse-snatching suspects tried to convince police they weren't anywhere near the victim.
Unfortunately for the suspects — now facing robbery charges — crisp, digital images from the Oakland train station's new surveillance cameras caught them in a lie.
Similar cameras are being installed in another two of the San Francisco Bay Area Rapid Transit's busiest stations. The surveillance system represents the latest in video technology, the kind also cropping up in schools, street corners, even restaurants.
"The images are much better," BART police Sgt. Frank Lucarelli said. "You can blow them up, and they don't degrade as much."
It's a far cry from BART's old patchwork of cameras, which produced the blurry, hard-to-follow shots often seen on television crime shows.
The latest setup features live streaming video with sharp, color images at up to 500 lines of resolution, compared with the old system's 160 lines in black and white. Only partially installed, the new system has already yielded footage that helped police solve 10 crimes.
Once fully in place, the equipment will allow police or dispatchers to remotely monitor and control the cameras, zooming in on trouble spots from headquarters miles away.
Digital surveillance systems are growing more powerful, less expensive — and increasingly common.
To privacy advocates, they are ominous and invasive.
"Whether it's the Big Brother of government or the little brother of industry, both pose a threat to our privacy," said Barry Steinhardt, associate director of the American Civil Liberties Union.
Revenues related to video surveillance more than tripled from $282 million in 1990 to more than $1 billion in 2000, and the Security Industry Association forecasts that they could grow to $1.63 billion by 2005.
The latest technology lets operators pan, tilt or zoom their cameras via the Internet or a company's computer network. A single monitor can simultaneously display images from up to 16 cameras, reducing the expense of multiple screens.
Finding a particular image used to mean hours of scrolling through analog tapes. Doing it digitally takes less than a minute.
"These cameras are so good today, and the software to control and record them is available at a reasonable cost," said Dale Scheideman, planning director of the Clark County School District in Nevada.
Using a laptop, he said, "I can sit in the parking lot of a school and can view the inside of the school."
The Las Vegas-area district is spending $16 million to install the cameras in 250 schools. With a camera that can zoom in on license plates from 100 yards away, Scheideman said, school officials recently caught a young man trying to break into a car.
"Business is booming," said Patrick Blair, a vice president with Vital Link Business Systems. The San Francisco-based company provides monitoring services to restaurants, allowing owners to watch their kitchens and dining areas over password-protected Internet connections.
Vital Link opened two years ago and claims 2,500 customers nationwide. The equipment costs several hundred dollars to install and $250 per month for a standard four-camera package.
Century Fast Foods is outfitting its 41 Taco Bell franchises in Southern California with monitoring systems to keep an eye on customer service and employee theft — a common problem in the transient fast-food work force.
"I could go on vacation and still watch my restaurants," said Jim Clark, the company's vice president of operations.
Another start-up, Vantum Corp. of Boulder, Colo., has a remote video monitoring system that can begin recording automatically in response to motion, a light turning on, or distinct sounds such as breaking glass.
The systems, which cost from $1,295 to $1,995 apiece, can trip an alarm or send alerts by page, e-mail or telephone.
Within a year, operators of Vantum's cameras should be able to program them to follow the movements of a given object or person.
"This stuff isn't science fiction anymore," said Howdy Pierce, the company's chief executive.
Government-backed surveillance systems are perhaps the most controversial, leading to fears of an Orwellian society.
Al Greening, a San Francisco resident and BART rider, understands the desire of law-enforcement officials to keep subways and streets safe.
"But I'm a little apprehensive of the Big Brother aspect, too," he said. "It hasn't gone too far yet, but I could see where it could."
The number of U.S. cities with locally approved street surveillance is unknown. But such surveillance has become more common since a 1997 California Research Bureau report counted at least 13 cities from Tacoma, Wash., to Dover, N.J.
In June, for instance, California's Simi Valley approved a grant to install cameras to catch graffiti vandals. Palm Springs voted to seek similar funds.
In addition, more than 60 U.S. cities are using traffic cameras to photograph motorists who drive through red lights. Richard Retting, senior transportation engineer at the Insurance Institute for Highway Safety, said only a handful of such cities existed in 1997.
"With the exception of very rural states, all are drafting or pushing for state laws" allowing red-light cameras, Retting said.
Some 400 motorists are challenging the constitutionality of red-light cameras in San Diego.
America still lags behind Britain, where more than 300 jurisdictions use public video surveillance. Last fall, London police began prowling the entertainment — and crime — hot spots of Soho and the West End in a van armed with nine cameras.
For now, the video eyes spreading across the United States remain a hodgepodge of individual systems. The ACLU worries about a future in which such systems are so linked that someone's identity and whereabouts could be tracked with a few computer commands.
Various efforts are underway to develop the necessary tools.
Colorado's Department of Motor Vehicles this month said it planned to buy cameras and map the faces of drivers to curb identity theft and fraud, contributing to a growing number of government databases of facial images.
And a few weeks ago, Tampa, Fla., became the first U.S. city to install surveillance cameras that scan faces and match images with a database containing 30,000 mug shots of people wanted by police.
Some European cities already use face-recognition technology. Tampa used a similar system in January, picking out faces of 19 petty criminals from among the 100,000 fans at the Super Bowl.
For the Privacy Foundation's Richard Smith, the Tampa project looks like an ominous prototype: "Ten years from now, do we really want to live in a country where face matching is done routinely in public places?"