An electronic bracelet, strapped to a parolee's ankle, uses Global Positioning Satellite (GPS) technology to track his or her every move. It alerts a parole officer if a convicted sex offender is near a school, for instance, or if a drunk driver steps into a bar.

Oklahoma may well be the next state to use this technology to keep prison populations - and prison costs - down. Just this week, a bill passed both houses and is awaiting the governor's signature.

The number of states using this technology has multiplied in the past few years - a direct result of the limping economy, says Lee Kicker, western regional sales manager for Pro-Tech, the company which contracts the technology.

"Our biggest success has been in getting heads off beds," says Mr. Kicker, referring to municipalities that are looking to release inmates early.

"Compared to a jail bed, it's dramatically cheaper."

The Florida Department of Corrections first began using the technology in 1997, and currently 32 states and 125 different jurisdictions utilize this system. The savings - GPS costs an average of $5 a day compared to $50 a day in prison - is significant.

But some wonder about the wisdom of letting inmates out early - even if it's only nonviolent offenders, as will be the case with the Oklahoma Department of Corrections. The state wants to send 800 offenders now on work release home with a GPS tracking device and move 800 inmates in prison to work release. All of them could be monitored with the technology.

"We're not in favor of taking people out of prisons and putting them on GPS," says Kicker, a former Dallas police officer. "But many people, like those on work release, can do just as well out on the street as they can in prison."

Some jurisdictions use GPS to monitor parolees or those on probation. Some, such as Tulsa County, use it to monitor people awaiting trial. There, the county assesses the danger and flight risk and then decides whether to let someone out with an ankle bracelet.

Officials there have monitored over 1,000 people so far, with charges ranging from domestic abuse to drugs to murder. In that time, only seven have failed to appear in court and six were captured within 48 hours.

"They usually test us for the first couple days, but when they realize that we truly do know their whereabouts at all times, they behave themselves," says Kevin Francis, director of court services for Tulsa Country.

He calculates that the GPS tracking system has already saved taxpayers $3.2 million annually - enough to fund his entire office for a year.

GPS sends back signals and data in real time, which is a far cry from old tracking systems. Parole officers input curfew times and exclusion zones, such as a playground, a victim's house, or a bar, into a computer and are beeped if an offender enters that area.

In Colorado, for instance, a convicted sex offender was found frequently returning to the scene of his crime. One of the first signs of reoffending, experts say, is fantasizing about a prior offense, so the man was sent back to prison for violating the terms of his parole.

Studies have shown that satellite-tracking systems can reduce the number of parolees who commit crimes. In Florida, where the system has been in operation longer, recidivism rates among sex offenders have gone from around 50 percent to between 3 and 7 percent.

The American Civil Liberties Union (ACLU), though it's concerned about the monitoring of people who might not be included if the GPS tracking wasn't an option, says the technology is a good alternative to incarceration.

The US has over 2 million people in custody and the rate of incarceration is several times that of most industrialized nations, says Elizabeth Alexander, director of the ACLU's National Prison Project in Washington.

"We need to reform our criminal-justice system and be certain that we are using our scarce resources on prisons only when it is absolutely necessary," she says. "So we support alternatives that do that - and protect the public's safety."

But the system is not foolproof. Like any technology, it's subject to human error. Here in Houston, for example, convicted rapist Lawrence Napper was placed on the GPS system after being paroled in 2000.

He was supposed to go only from home to work to his parole office, but in nine months, he logged 444 violations that were never caught. He was then transferred to a less restrictive monitoring program and, a month later, was arrested for sexually assaulting a 6-year-old boy. He was sentenced to life in prison.

"There is a chance for human error. I'm not going to argue that point," says Kicker. "But you can't strap an ankle bracelet on a guy and then forget about him. It takes a certain amount of diligence on the parole officer's part."

Full HTML version of this story which may include photos, graphics, and related links