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Monitoring High-Risk Sex Offenders With GPS Technology: An Evaluation of the California Supervision Program

A great deal of controversy surrounds the management of sex offenders. Moral outrage and fear on the part of the public have set the stage for the growth of strict laws, restrictive policies, and severe sentences for sex offenders. The monitoring and supervision of this population is particularly important because of the irrefutable harm that sexual victimization causes and the potentially volatile community responses to the release of sex offenders.

The purpose of this evaluation is to determine the effectiveness of the global positioning system (GPS) monitoring of high-risk sex offenders (HRSOs) who are placed on parole. The California Department of Corrections and Rehabilitation (CDCR) began using GPS to monitor sex offenders in June 2005 when CDCR implemented a 2-year pilot program using a 500-unit system to monitor and track the movement of HRSO parolees. In November 2006 with the passage of California Proposition 83, better known as Jessica’s Law, the state mandated that all sex offenders be placed on GPS supervision for life and that CDCR parole agents be responsible for enforcing the terms and conditions while a parolee is under the state’s jurisdiction.

This study integrates both outcome and process evaluation components. The outcome component assesses the impact of the CDCR GPS supervision program by employing a nonequivalent-group quasi-experimental design with a multilevel survival model. In addition, a propensity score matching procedure was used to account for the differences between the treatment and comparison groups. The sample includes 516 subjects equally divided between the treatment and control groups.

The subjects in the GPS group demonstrate significantly better outcomes. In terms of compliance, the multivariate model shows that the hazard ratio of a sex-related violation is nearly three times as great for the subjects who received traditional parole supervision as for the subjects who received the GPS supervision. In terms of recidivism, compared with the subjects who received the GPS monitoring supervision, the hazard ratio for any arrest was more than twice as high among the subjects who received traditional parole supervision.

The cost of GPS program is roughly $8.51 per day per parolee more expensive than traditional supervision. However, the outcome results favored the GPS group in terms of both compliance and recidivism. In other words, the GPS monitoring program is more expensive but more effective.

The GPS program was implemented with a high degree of fidelity.

The final report is available at https://www.ncjrs.gov/pdffiles1/nij/grants/238481.pdf.

An Evaluation of Using GPS Technology for Supervising High-Risk Gang Offender Parolees

The impetus for this project occurred in July 2005 when the California Department of Corrections and Rehabilitation (CDCR) began a pilot program in San Diego to test the use of global positioning system (GPS) technology to monitor high-risk sex offenders on parole. The success of this pilot project prompted CDCR to enter into a partnership with the city of San Bernardino to implement a similar project to track the movements of known gang members. In May 2007, Gov. Arnold Schwarzenegger proposed an antigang initiative—known as the California Gang Reduction, Intervention, and Prevention (CalGRIP) program—to provide more than $48 million in State and Federal funding for local antigang efforts, including job training, education, and intervention programs. CalGRIP expanded the 20-unit CDCR pilot program in San Bernardino to an 80-unit program by adding 20 units each in Sacramento, Fresno, and Los Angeles. The program was further expanded in 2008 by doubling the capacity to 160 units through the addition of 60 units in Riverside and 20 units in Los Angeles County.

The purpose of this study is to assess the impact, fidelity, and costs of the CDCR GPS program, including its effectiveness both as a strategy for reducing recidivism and as an investigative and prosecutorial tool. The study proposes a nonequivalent-group, quasi-experimental design with multilevel modeling. The treatment group includes all high-risk gang offenders (HRGOs) placed on the GPS monitoring technology in each of six specialized gang units in San Bernardino, Sacramento, Fresno, Riverside, the city of Los Angeles, and Los Angeles County from March 2006 (the program start date) through the study start date (December 2009). The comparison group is constructed with data from CDCR tracking systems to create a pool of gang offender parolees from each of the six areas that have not been placed on the GPS monitoring technology. The study population is conservatively estimated to be 714 (357 treatment and 357 comparison parolees). A propensity score is being used to estimate the probability of assignment to the treatment group from several pretreatment characteristics selected a priori to present a broad spectrum of pretreatment risk factors.

Five primary data sources are accessed to measure variables:

This data is being collected through a variety of methods including the extraction of data from the California Department of Justice data management systems and GPS vendors as well as site visits and record reviews. The hard copy of all subject-related data (e.g., RAP sheets, data collection forms, and staff interview transcripts) is being stored in a locked file cabinet located in a private location. The electronic data is stored in a central evaluation data repository located on a partitioned drive permitting only project researchers who have signed confidentiality forms to access the data.

The study is evaluating the impact of the GPS monitoring of HRGOs using a quasi-experimental design that features a propensity score to model the selection process. It is hypothesized that the GPS technology will deter parolees from engaging in future criminal behavior because it increases the probability of detection, encourages parolees to be more compliant, serves law enforcement in investigating a reported crime, and supports prosecutors in building a case by providing stronger evidence.

The outcome measures include a) recidivism, b) compliance, and c) effectiveness as an investigative and prosecutorial tool. The central feature of the analysis uses survival analysis to model all time-to-event data.