Moldenhauer, the agent in charge of the county's probation office, knows to within 10 feet where predators were yesterday at 6 p.m. and today at 6 a.m.

"In terms of monitoring someone 24-7 without having an agent to their side, this is a very good surveillance tool," she said.

Real-time tracking of sexual and violent criminals by satellite is the crux of a new small-scale program being implemented across South Carolina. The launch comes less than a year after problems with a Charleston man's monitoring device prompted a statewide investigation into their effectiveness.

The concept attracted the interest of a local lawmaker after the story broke that a sexual offender in Florida admitted to kidnapping and killing a 9-year-old girl who lived nearby. Last week, three weeks after the girl disappeared, the offender confessed to the crime.

The Florida case could have been solved sooner if offenders were monitored as they are under the new state program, said officials at the South Carolina Department of Probation, Parole and Pardon Services.

The program, which began in mid-February, is a limited initiative. The $100,000 federal grant that started it means only 100 to 200 people can be tracked at one time. Only those on probation or parole for domestic violence or sexual crimes where the victim was an adult female are eligible, according to the grant's language, said Peter O'Boyle, spokesman for the state probation department.

So far, 10 counties with 18 to 20 offenders are being monitored statewide. Five offenders in Charleston County are being tracked. Most counties should have the system by the end of the year, O'Boyle said.

"We're being careful with the technology because it's new," he said. "We plan to roll it out in every county as training and equipment progresses."

Sen. Robert Ford, a Charleston Democrat, introduced legislation Tuesday to require every sex offender on probation to wear a satellite tracking device.

Ford said the current program is "hardly sufficient. That small-scale stuff they've done is a drop in the bucket. We can wait until someone gets killed like in Florida or we can do something."

Ford and other proponents of the technology believe the monitoring systems could alleviate crowded prisons. Nonviolent offenders, such as those incarcerated for failing to pay child support, could be released with one of these devices, they argue.

Sherri Benard, president of Alternative Solutions to Incarceration, which markets the monitoring devices, recently presented the idea to the Charleston County Council and plans to make a similar pitch to the Charleston City Council soon.

The satellite tracking systems have created some problems in the past.

In May 2004, the State Law Enforcement Division opened an investigation into the use of monitoring devices by local bail bondsman Larry Ballard. The battery in one client's device kept signaling a power failure and going offline.

O'Boyle defended the mechanism's effectiveness, saying it is up to the offenders to charge the batteries, as a condition of their probation or parole.

"It's fail-safe in the sense that tamper with the device or don't charge the battery, we get a message," he said, adding that when it goes dead, "we'd have to go look for them like any other fugitive."