How GPS bracelets keep track of sex offenders


Corrections officers say GPS monitoring devices play a valuable role in tracking locations and patterns of sex offenders. This offender is in the middle of a three-year sentence and says the device helps him stay out of trouble. 

The state Department of Corrections uses GPS monitoring to keep track of sex offenders at high risk of reoffending. Ankle bracelets transmit signals via satellite when the offenders venture into places they're supposed to avoid. So long as they do only what they should, tracking them should be dull, say state authorities.

-----By Christine Clarridge 

Seattle Times staff reporter


Tracking convicted sex offenders as they go about their daily routines should be dull.

If they’re doing what they’re supposed to be doing — going to work, returning home, shopping for groceries and avoiding “exclusion zones” — then “it’s like watching a really boring movie,” said Jeff Brown, one of about 10 state Department of Corrections (DOC) officers who supervise King County’s high-risk offenders who wear GPS monitoring devices.

Brown and other DOC officers follow offenders via a satellite transmitting signals sent by GPS bracelets. The signals are sent to computers, which display the offenders’ whereabouts via an online map.

The computers receive a signal each minute, providing officers with a road map of where offenders have been.

Even when not watched in real time, the GPS ankle bracelet transmits signals when an offender ventures into a place he or she is supposed to avoid, such as schools or parks where children congregate.

“The only way a person can offend sexually is to have a cloud of secrecy around them,” said Theo Lewis, supervisor of King County’s Special Assault Supervision Unit. “This blows that cloud away, and it’s highly effective in allowing the CCO [community corrections officer] to intervene before they get to a point where they are going to reoffend.”

The DOC’s use of GPS monitoring has come under fire in recent months. In March, a level 3 sex offender in Snohomish County cut off his GPS monitoring bracelet and left the state.

In February, a 13-year-old girl was killed in a field near Vancouver, Wash. A level 3 sex offender — a designation for those considered most likely to reoffend — who was wearing a GPS bracelet has been charged in her slaying.

Critics point to the Vancouver slaying, saying GPS monitoring does not alert corrections officers when an offender commits a violent act, but merely indicates their location. They also say it gives the DOC a false sense of security because tracking an offender’s location only provides a part of the story.

DOC officials readily concede GPS monitoring devices aren’t foolproof.

Officers don’t sit at computers 24 hours a day monitoring every offender under their watch. Instead, they say tracking the location of offenders via satellite signals is a valuable tool to help parole officers keep tabs on high-risk offenders.

“When we are tracking clients we use every tool available: documented offense patterns, risk-assessment data, treatment providers, local law enforcement, family members, polygraph examinations, home visits, drug testing and behavior-modification programs,” King County’s Lewis said.

Chad Lewis, a DOC spokesman, said, “We’ve said all along that no technology, including GPS, can prevent an offender from committing a new crime. It can, however, help our officers hold offenders accountable for where they’ve been. Before GPS, it was more difficult to know if an offender had been somewhere he is not allowed to be.”

In the case of the Snohomish County offender who removed his GPS bracelet, DOC officials said the offender’s parole officer knew within hours that his device had been cut off and a nationwide arrest warrant was issued. The man was arrested in Texas.


Slaying prompted use


After the 2007 slaying of 12-year-old Zina Linnik of Tacoma at the hands of convicted sex offender Terapon Adhahn, Gov. Chris Gregoire urged the state to use the GPS devices on sex offenders who have been deemed to be at high risk to reoffend or who are homeless.

There are currently 123 offenders on GPS monitoring in the state, Chad Lewis said.

The DOC uses the devices to monitor movements of mostly level 3 offenders and homeless offenders considered likely to reoffend. Some level 2 offenders who need special attention also are fitted with the device.

A similar, but smaller, device frequently is used by municipal courts to impose a form of house arrest on people arrested for lesser charges, typically for driving while under the influence of an intoxicating substance.

The rechargeable monitoring device, which is clunky, thick and about the size of an old-school cellphone, is fitted around an offender’s ankle with a thick, rubberized band.


The device recieves a signal from GPS satellites and then sends that information via a cell phone communications network to a computer program that collects the data. The offender’s parole officer can watch the client’s movement in real time or track the history of the offender’s movements.


The officer can log on to the computer, pull up the offender’s personalized program and track the offender’s movements on a map.


A green dot shows the offender’s location, and a green arrow indicates when the offender is on the move. The program also can tell the officer how fast the offender is moving.


The monitoring devices usually are set up to vibrate or buzz whenever the wearer goes into preprogrammed “exclusion” zones, such as schools and parks, or “inclusion” zones, such as the offender’s home or work.


In addition to at least one visit with the offender at his or her home each month, parole officers typically log into a computer several times a day to take a look at movements of the 20 to 30 offenders they each supervise.


As Brown, the DOC officer, said, the duty should be boring.


If it’s not, if there’s any variation in routine or deviation from the norm, a closer look is warranted.


Changing behavior


According to Theo Lewis, the majority of his unit’s clients do not reoffend while under supervision. While most people cannot be cured of a propensity for sex crimes, he said, many offenders can learn strategies to change their thinking and overcome their impulses, similar to the way an addict learns to avoid relapse.


It’s not uncommon for parole officers to see that an offender has visited someone at a new address. When that happens, the officer can look up the address, find the resident and either call them or pay a visit to tell them about crimes committed by their new friend.


Many offenders who wear the devices say that, once they get used to wearing the anklets, they welcome them.


Some say the entire process — the arrest, the treatment and the accountability forced by the GPS device — actually has saved their lives.


Jonathan Freddie, 24, was convicted of having sex with a 15-year-old girl when he was 20 and of communicating with a minor for immoral purposes. He will be wearing his monitoring device for two more years, he said.


He said he considers his offense a youthful mistake and that he never wants to go back to prison or jail.


“Things are already stacked against me,” Freddie said. “I don’t want them to get any worse. The monitor helps me tell people the truth about my past, and it gives them a chance to run away screaming when I explain why I wear it.


“It’s also gotten me out of trouble by proving that I didn’t do something I was accused of, and it’s a reminder to me to stay on the path I’m supposed to be on.”


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