Sex Offenders Monitored by GPS Found to Commit Fewer Crimesby Philip Bulman
An NIJ-sponsored research project examines the impact that GPS monitoring has on the recidivism rates of sex offenders in
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A study of California high-risk sex offenders on parole found that those placed on GPS monitoring had significantly lower
recidivism rates than those who received traditional supervision.
Researchers examined the effectiveness of using GPS to monitor high-risk sex offenders placed on parole in California. The
NIJ-sponsored study included 516 high-risk parolees who had been released from prison between January 2006 and March 2009.
Half of the parolees wore GPS monitoring devices in addition to receiving traditional parole supervision, which involves regular
contact by parole agents and weekly sex-offender treatment classes ("GPS group"); the other half received only traditional
parole supervision ("traditional group"). Researchers tracked each parolee for one year following his initial parole date.
The study involved:
- An outcome evaluation to assess both the cost of the GPS program and its effectiveness in reducing the criminal behavior of
high-risk sex offender parolees.
- A process evaluation to assess the program's design and implementation.
The researchers collected information from the state's data management system and examined official arrest records, parole
supervision records, GPS monitoring data and state cost information. In addition, they conducted a survey of roughly 1,000
California Department of Corrections and Rehabilitation (CDCR) parole officers. The survey included questions about the GPS
monitoring system, caseloads, program staffing and screening of high-risk sex offender parolees.
GPS More Expensive, but Also More Effective
The researchers found that parolees in the traditional group — those not placed on GPS monitoring — committed new crimes and
had their parole revoked more often than did parolees in the GPS group. In addition, the traditional group returned to custody
at a rate 38 percent higher than the GPS group.
The cost analysis showed that in California, monitoring parolees using GPS costs approximately $35.96 a day per person, while
the cost of traditional supervision is about $27.45 a day. The GPS program is more expensive but more effective. Although
the GPS program costs $8.51 more per day than traditional supervision, the GPS approach produced a decrease of 12 percentage
points in arrests for any offense (from approximately 26 percent to 14 percent). In addition, offenders who were monitored
using GPS complied with the terms of their parole at higher rates than did offenders on traditional parole.
The cost of California's GPS monitoring is lower than the cost of moving parolees to "indefinite civil commitment," which
entails sending sex offenders whose prison sentences are over, but who are believed to be too dangerous to release into the
community, directly from confinement in prison to confinement in dedicated institutions. Such civil confinement programs can
cost an average of more than $100,000 a year per person because of the programming that must be provided.
The researchers also examined the degree to which the GPS program delivered services as designed. Through a process evaluation
that looked at responses from the survey of parole agents as well as GPS monitoring data, they found that CDCR had developed
a protocol for the GPS program and largely followed that protocol while implementing the program. Based on their findings,
the researchers made several recommendations.
Reexamine the identification of high-risk sex offenders. To identify high-risk populations, California currently uses the standardized Static-99 risk instrument, which measures "static"
factors that do not change over time (see related article, "Predicting Recidivism Risk: New Tool in Philadelphia Shows Great Promise"). However, in the survey of parole agents, nearly half of respondents said that the Static-99 does a poor job of identifying
high-risk sex offenders. The researchers noted that the current risk instrument may predict recidivism, but those convicted
of noncontact offenses such as exhibitionism pose less of a threat than do rapists and child molesters. Thus, the researchers
recommend using a system that accounts for the different recidivism risks among offenders and the varying threats to public
Monitor attendance at treatment classes. CDCR mandates that high-risk sex offender parolees attend weekly treatment classes. However, the researchers found a disconnect
between parole agents and service providers in terms of tracking treatment attendance; 100 parolees had no record of attending
treatment during the study period. Further, in the survey of parole agents, only 75 percent of agents said that their parolees
attended treatment at least once a week. Previous research indicates that the meticulous monitoring of sex offender treatment
is an important facet of sex offender supervision and that sex offenders who stop attending treatment have higher recidivism
rates. The researchers recommend that parole authorities strictly monitor and enforce weekly class attendance.
Use graduated sanctions that balance cost and risk. Instantly sending someone back to prison for a minor violation is costly. GPS supervision costs $35.96 daily, whereas the
cost of keeping someone in a California prison is about $129 per day. The researchers recommend that CDCR — rather than issuing
blanket parole revocations and sentencing violators to go back to prison for a few months at a time — employ a graduated sanctions
system for dealing with parole violations. Such a system weighs the gravity of the offense against the need to preserve public
safety, thereby increasing the likelihood that a parolee with a serious violation is incarcerated, while one who presents
less danger is still sanctioned but in a less restrictive, less costly manner (for example, by imposing a home curfew on the
offender). The researchers added that California is in the process of piloting a new, structured decision-making system for
dealing with parole violations, which will allow parole agents to scientifically weigh an offender's risk level and the benefits
of alternatives to prison as part of their decision-making process.
Mandate the use of zones. The researchers also found that parole agents were neglecting to use inclusion and exclusion zones. Such zones are intended
to keep parolees either within certain areas, such as home and work, or away from certain places, such as schools or parks
that attract many children. In the process evaluation, the researchers found that only 60 percent of parole officers always
or often discussed the limits of inclusion zones, and only half discussed exclusion zone limits. The researchers argue that
the use of zones may be the most important GPS tool because the application of zones allows parole officers to be alerted
to specific offender movements. Thus, they recommend making the zones compulsory.
Use a monitoring center to screen alerts. The large majority of parole agents (89 percent) reported in the survey that GPS monitoring was more time-intensive than
traditional supervision. Until fairly recently, officers were receiving alerts when offenders tampered with the GPS device
or committed other detectable violations. These alerts might also have included incidents such as an offender being in the
basement of a building, sounding an "alarm" simply because someone was out of reach of the GPS monitoring system for a few
minutes. From January 2009 until December 2010, paroled California sex offenders generated 1.5 million alert notifications.
The researchers noted that according to an internal CDCR document, officers spend 44 percent of their time monitoring movements
by GPS and only 12 percent of their time in the field.
To help remove the burden on agents of responding to "minor" alerts, California switched to a centralized monitoring system
in 2011. Under the new system, two vendor-operated centers screen the thousands of GPS alerts that agents receive each month
and respond to the more technical alerts, such as a battery that has run too low. The centers forward alerts that are more
serious to parole officers, allowing officers to focus more closely on direct supervision and on responding to real threats
to community safety.
Limit caseload to 20. GPS increases the information that officers receive about parolees, but reviewing this information is time-consuming and
reduces the time available for direct supervision. As noted, agents spend only about 12 percent of their time in the field.
According to the researchers, the best way to ensure that parole agents have sufficient time to directly supervise offenders
is to limit the caseloads of GPS parole agents. In fact, the researchers found in their outcome evaluation that the size of
the caseload was correlated with parole violations and with parolees returning to custody. Therefore, the researchers recommend
smaller caseloads of no more than 20 people per officer.
Issues and Concerns
Finally, the researchers noted that GPS monitoring is not a panacea. The systems can give false positives for violations.
For example, sometimes a monitored offender "disappears" simply because he is in an underground location, forgets to recharge
the battery that powers the system, or even decides to go to sleep under an electric blanket that disrupts the GPS signal.
In these instances, the system would send an alert even though no criminal activity was taking place.
The researchers also pointed out other possible limitations of their work. The study lasted only a year, and results may vary
over longer periods. In addition, at least one previous study found that once the GPS monitoring ends, offenders who had been
monitored by GPS do just as poorly as other offenders.
Researchers at Development Services Group, Inc., of Bethesda, Md., and Old Dominion University in Norfolk, Va., conducted
the study of California parolees. Read their final report to NIJ, Monitoring High-Risk Sex Offenders With GPS Technology: An Evaluation of the California Supervision Program (pdf, 114 pages).
NIJ Journal No. 271, February 2013
About the Author
Philip Bulman is a writer and editor at NIJ.
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Date Created: February 27, 2013