Updated

Three decades after they were introduced as a crime-fighting tool, electronic ankle bracelets used to track an offender's whereabouts have proliferated so much that officials are struggling to handle an avalanche of monitoring alerts that are often nothing more sinister than a dead battery, lost satellite contact or someone arriving home late from work.

Amid all that white noise, alarms are going unchecked, sometimes on defendants now accused of new crimes.

Some agencies don't have clear protocols on how to handle the multitude of alerts, or don't always follow them. At times, officials took days to act, if they noticed at all, when criminals tampered with their bracelets or broke a curfew.

"I think the perception ... is that these people are being watched 24 hours a day by someone in a command center. That's just not happening," said Rob Bains, director of court services for Florida's Ninth Judicial Circuit Court, which this spring halted its monitoring programs after two people on the devices were accused in separate shootings.

At least 100,000 sex offenders, parolees and people free on bail or probation wear ankle bracelets that can sound an alarm if they leave home without permission, fail to show up for work or linger near a playground or school.

To assess these monitoring programs, The Associated Press queried a sample of corrections, parole and probation agencies across the U.S. for alarms logged in a one-month period and for figures regarding the number of people monitored and the number of officers watching them. The AP also reviewed audits, state and federal reports and studies done of several of these programs, which detailed problems that included officers failing to investigate alarms or take action when offenders racked up multiple violations.

Twenty-one agencies that responded to the AP inquiry logged 256,408 alarms for 26,343 offenders in the month of April alone. It adds up for those doing the monitoring. The 230 parole officers with the Texas Department of Criminal Justice handled 944 alerts per day in April. The Delaware Department of Correction, which has 31 field officers, handled 514 alarms per day.

"When we first introduced this technology ... officers thought they were just going to go play golf for the day," said Jock Waldo, a spokesman for Boulder, Colo.-based BI Inc., which produces about half the bracelets used in the U.S. However, the devices require scrutiny of the vast amount of data they produce, Waldo said.

Sorting through alerts, and deciding which are serious enough to merit a rapid response, can be fraught with peril.

In Syracuse, N.Y., federal probation agents wary of alarms caused by things such as lost satellite signals asked a monitoring company to contact them only if an alert lasted more than five minutes. Agents tracking child-porn suspect David Renz then missed 46 alerts in nine weeks, including one generated when he removed his bracelet in March. He then raped a 10-year-old girl and killed her mother. Renz pleaded guilty to those charges July 17.

Corrections officials in Orange County, Fla., were so inundated with alerts that they halted all real-time notifications except when people tried to remove their bracelets. That allowed Bessman Okafor, awaiting trial for a home invasion, to violate his curfew 53 times in a single month without any action being taken. During one of those outings last September, prosecutors say, Okafor shot three people, killing a 19-year-old man who was to testify against him.

In Colorado -- where the state's 212 parole officers handle an average of 15,000 alerts a month -- one officer took five days to check on the whereabouts of a paroled white supremacist after getting an alert that he had tampered with his bracelet. By the time officers issued an arrest warrant, the man had killed two people, authorities say, including the head of the state's Department of Corrections and Nathan Leon, a computer technician and pizza delivery driver.

"I hurt as much now as I did four months ago," Leon's father, John Leon, said last week. "Technology is not going to automatically issue warrants for people. It just sends an alarm that says, `This thing's been cut.' And for people to ignore it, what's the point?"

Supporters of electronic monitoring say such tragedies are the exception and that the devices are a valuable tool for authorities who previously relied only on shoe leather and the telephone to keep tabs on released prisoners. In many cases involving violence by people on trackers, the accused likely would have been free on bail or parole even if electronic monitoring didn't exist, and would have been far harder to monitor.

"No one should think this is going to be 100 percent effective," said George Runner, a former California legislator who wrote that state's voter-approved law requiring bracelets for all paroled sex offenders. "It's just a tool. When used, and used effectively, it can be not only helpful in modifying behavior, but we've heard stories about it actually preventing crimes."

Once used to track straying cows, electronic monitoring of criminals debuted in 1983, when a New Mexico judge inspired by a Spider-Man comic book allowed a man who violated probation to wear an ankle bracelet rather than go to jail. Use took off in the last decade, as technology improved and lawmakers became enamored of trackers as a cost-effective alternative to incarceration and a way of monitoring sex offenders for life.

Today, 39 states require monitoring of sex offenders. The biggest user of ankle bracelets is the federal government, which tracks people on pretrial release and probation, as well as thousands of immigrants fighting deportation.

Two types of devices are primarily used: radio frequency monitors that generate an alert when a wearer strays from a fixed location, such as a home, and GPS units that can track wearers all over town. Those GPS units can be set to sound alerts in real time or passively collect data for review later.

Manufacturers stress that these devices were never intended to be foolproof.

Most are designed to be cut off easily -- in part because they could interfere with medical equipment  -- but they are made to send alerts anytime someone attempts to stretch or slice a strap. And while GPS devices allow users to pinpoint an offender's location on a computer map in real time, most officers are too busy to check until they get an alarm indicating a potential problem.

"It's virtually impossible to sit there and track a person all day," said Kelly Barnett, a union official who represents probation officers doing GPS tracking in Michigan. Barnett said that while officers see value in the monitoring, such programs also give "a false sense of security to the community."

Studies have found mixed results on the devices' value as a crime deterrent. Bill Bales, a criminology professor at Florida State University, said he believes they are beneficial. Offenders wearing them tend to stay home more with their families.

"They're glad to be in the free world, albeit tethered, rather than in prison," Bales said.

The key to making the devices work, he and other experts said, is to figure out how best to process the immense amounts of information they generate.

The AP inquiry of correctional agencies found that policies on how to handle alerts vary. In Kentucky and Ohio, state probation or parole officers only respond to alerts during regular business hours. In other places, coverage exists around-the-clock.

Some agencies hire monitoring companies to do an initial screening of alarms. Others tackle that task themselves.

In many cases, alerts about things such as low batteries or lost GPS signals can be resolved by asking an offender to recharge or go to a window to recapture the satellite signal. Alerts that can't be resolved immediately are usually sent to field officers through pages, texts or emails. In most states, officials rarely respond in person because so many alerts can be cleared with a phone call.

While many agencies have detailed protocols in place, others have none.

In Florida, after a man on a GPS monitor was accused in an Easter Sunday shooting in the city of Apopka, administrators in the state's Ninth Judicial Circuit Court pointed to a "lack of procedures" for handling alarms.

In a June 7 report, court administrators said the small monitoring company that had been watching the suspect had just one person on call to track 81 people, and no system for notifying law enforcement or the courts about GPS violations. After the shooting, it took six hours for the company to notify anyone that the suspect had removed his tracker and disappeared.

Even when procedures are in place, they aren't always followed. For example, a 2010 audit of the federal probation office in northern New York found lapses that included officers not making their required number of in-person visits with people in monitoring programs.

A new review conducted after Renz cut off his bracelet found that even though his monitor had sent multiple tamper alerts over several weeks, officers neither inspected his equipment nor documented the alerts in his case file.

"In most instances, the probation office took no action in response to the alerts at all. When action was taken, it was limited to the probation officer verbally admonishing the defendant to `stop messing with the transmitter,"' the report said.

In a June 14 letter to a New York congressman, Judge Thomas Hogan, director of the Administrative Office of the U.S. Courts, said Renz was not supervised in a typical manner, and that the office had since made substantial changes, including reorganizing the monitoring unit, retraining staff and "dismissing and demoting certain probation office personnel."

In Tennessee, a government audit last summer looked at a sample of 68 GPS offenders and found that officers with the state's Board of Probation and Parole had failed to clear or confirm 80 percent of the 11,347 alerts they generated over 10 months. That included thousands of alarms set off by people leaving home when they weren't supposed to or entering places they had been told to avoid.

The report also found that offenders placed on monitors because they were deemed to need extra supervision actually got less because corrections officials routinely skipped tasks such as verifying that sex offenders were attending mandatory counseling sessions.

In response, the state Department of Correction noted that officers in the tracking unit had an average caseload of 40 offenders -- more than the 25 suggested by the American Probation and Parole Association. It also noted that a center that had been screening alarms 24 hours a day was closed due to budget cuts in 2011, at a time when state lawmakers had more than doubled the number of sex offenders required to get bracelets.

In several states, agencies are making changes.

After the March slaying of Colorado Department of Corrections chief Tom Clements, the state began requiring parole officers to respond to tamper alerts within two hours. The suspect in Clements' death, Evan Ebel, was killed in a shootout with Texas authorities.

In 2011, California began requiring the companies that provide ankle bracelets to sort routine alerts from more urgent ones to help overwhelmed parole officers. Still, earlier this year state officials admitted that thousands of sex offenders had slipped their bracelets and become fugitives.

Legislators there are pushing for more serious punishments for removing a bracelet. Said Democratic state Sen. Ted Lieu: "Dangerous parolees do not cut off their GPS devices because they want to go to church unmonitored."

U.S. Rep. Dan Maffei, a Democrat who represents upstate New York, said he wants to make it a federal crime to tamper with a monitor.

Since the Apopka and Okafor cases, the chief judge of Florida's Ninth Judicial Circuit Court has suspended nearly all electronic monitoring of criminal defendants while the programs are reformulated.

In the Okafor case, an internal affairs report found that officers in the Orange County Corrections Department program weren't on duty to respond to alerts after 9 p.m., and staffing was so tight that disciplinary hearings weren't scheduled for offenders with violations. One supervisor told investigators the monitoring equipment, supplied by 3M, was issuing so many email alerts that it had caused confusion about which were legitimate.

Chris Defant, a technology manager with 3M, said some users of the technology are still working to refine their procedures, while others have designed their policies in ways that generate few alarms.

In Florida, Orange County spokesman Steve Triggs said the real problem was such monitoring programs were "never really designed for the Okafors of the world." Prosecutors had argued at a bail hearing that Okafor was too dangerous to be released. Okafor has pleaded not guilty to the home invasion and the shootings. His lawyer, Joseph Haynes Davis, said his client is innocent. Okafor is behind bars awaiting trial.