Frank Ochoa, imprisoned on an attempted carjacking conviction, thought he had the guards fooled.

The inmate at a minimum-security prison in the California desert slipped his electronic bracelet around a hot cup of coffee and made a run for it.

Vincent campos, a correctional officer at Calipatria state prison in Calipatria, Calif., monitors inmates via a computer. The system records prisoners' whereabouts in real time thanks to bracelets prisoners wear in the experimental program.

Ochoa apparently didn’t know that by tampering with the tracking device, he had triggered an alarm at the Calipatria prison’s security control center. Guards caught Ochoa less than a mile away.

The sophisticated radio monitoring system that helped capture Ochoa two years ago is now being installed at a handful of other U.S. prisons. If widely adopted, it could one day change the way correctional facilities are run.

“It completely revolutionizes a prison because you know where everyone is not approximately but exactly where they are,” said Larry Cothran, a technology consultant to the National Institute of Justice.

Using radio transmitters monitored by a network of receivers, the system tracks prisoners and corrections officers to within 20 feet. Inmates wear tamper- and water-resistant bracelets while officers wear pager-like devices.

It’s a high-tech version of the head count, except these head counts are conducted every two seconds versus the method of five to eight times a day.

Any time an inmate tampers with or removes the bracelet or strays out of range the bracelet trips an alarm. Guards monitoring the prison can not only pinpoint the location but also know who is in the vicinity.

The monitoring device for officers has a red button that allows them to signal for help and an automatic “man-down” alarm if the device ends up in a horizontal position.

If guards aren’t careful, the tilt mechanism has been known to trigger alarms if the device gets twisted on their belt or they drop their pants, said Chris Trott, president of the Calipatria guards union.

“Sometimes you go to the bathroom and your alarm goes off,” he said.

Location data shows up as dots on a computerized map blue for corrections officers and yellow for inmates.

So far, Scottsdale, Ariz.-based Technology Systems International Inc. appears to be the only company selling such a product in the United States.