Tiny silicon chips were embedded into two workers who volunteered to help test the tagging technology at a surveillance equipment company, an official said Monday.
The Mexico attorney general's office implanted the so-called RFIDs — for radio frequency identification chips — in some employees in 2004 to restrict access to secure areas.
Implanting them in the workers at CityWatcher.com is believed to be the first use of the technology in living humans in the United States.
Sean Darks, chief executive of the company, also had one of the chips embedded.
"I have one," he said. "I'm not going to ask somebody to do something I wouldn't do myself. None of my employees are forced to get the chip to keep their job."
The chips are the size of a grain of rice and a doctor embedded them in the forearm just under the surface of the skin, Darks said.
They work "like an access card. There's a reader outside the door; you walk up to the reader, put your arm under it, and it opens the door," Darks said.
Darks said the implants don't enable CityWatcher.com to track employees' movements.
"It's a passive chip. It emits no signal whatsoever," Darks said. "It's the same thing as a keycard."
CityWatcher.com has contracts with six cities to provide cameras and Internet monitoring of high-crime areas, Darks said.
The company is experimenting with the chips to identify workers with access to vaults where data and images are kept for police departments, he said.
The technology predates World War II, but has appeared in numerous modern adaptations, such as tracking pets, vehicles and commercial goods at warehouses.
After Hurricane Katrina, as body counts mounted and missing-person reports multiplied, some morgue workers in Mississippi used the tiny computer chips to keep track of unidentified remains.