By Nicholas Corsaro, Robin S. Engel, Tamara D. Herold,. Murat Yildirim

The gang and gun violence reduction project implemented in Las Vegas consisted of three components: hot spots deployment, focused deterrence, and place network investigations. This report focuses on the development, implementation, and evaluation of the hot spots strategy. The hot spots strategy involved the strategic deployment of additional saturation police patrols in high-crime locations. Specifically, to address violent street crime, the LVMPD engaged in a 6- month (Nov 1, 2018 to Apr 30, 2019) cluster randomized controlled trial (RCT) design of street segments receiving additional hot spots deployment (saturation patrols) and streets receiving patrol as usual (control segments). All potential street segments were identified from an analysis of persistent violent crime hot spots (where intensive police focus has been paid by the violent crime unit officers since January of 2018). Researchers stratified highest risk and independent segments within chronic and persistent hot spot locations. Specifically, 22 treatment segments and 22 control segments were selected to form the evaluation. No treatment segment was within a block or intersection of another treatment or control segment to reduce potential contamination of findings. Deployment of officers to the treatment hot spots occurred via calls for service every day, randomly for a total of two hours of exposure at each hot spot. Officers were instructed to remain at the hot spot for a total of 15 minutes, which is the optimum time for deployment to achieve effects as identified by researchers (Koper, 1995). When reaching the hot spot, officers were also randomly instructed to either stay in their vehicle with the lights on, or patrol the segment on foot. Interviews with arrestees have shown police presence is understood and alters criminal behaviors in patrolled areas (Golub et al., 2003). However, hot spot patrols such as walking are likely to go unnoticed by ordinary citizens (Weisburd, Hinkle, Fameaga, & Ready, 2011). Therefore, using both treatment types (stationary with lights and foot patrol) likely leads to increased awareness of police, thereby reducing criminal activity. The control treatment was for business to occur as usual at the control street segments. Center researchers conducted fidelity assessments during the project implementation phase, in order to ensure that the strategy was being implemented properly. These assessments indicated a strong adherence to the research design. Specifically, the research design called for a total of 2 hours of saturation patrol (in 15-minute increments) each day. Analysis of all hot spot patrols revealed that approximately 1.5 hours of additional patrol was observed each day for 90% of all hot spots. A total of 2 hours of additional patrol as observed for 55% of all hot spots. These findings demonstrate that the LVMPD carried out the hot spots strategy as designed.

Alexandria, VA: International Association of Chiefs of Police, 2019. 43p.

By Robin S. Engel, Nicholas Corsaro and Tamara D. Herold

One of the most frequently used communication mechanisms associated with focused deterrence strategies are offender notification meetings, also referred to as “call-in” sessions. Typically, these meetings are used to communicate directly to offenders that their future violent behaviors (and those of their affiliated groups/gangs) will be responded to in a swift and predictable manner through a coordinated law enforcement effort to prioritize group violence, share information, and develop comprehensive group-focused responses (Engel, Tillyer & Corsaro, 2013). The purpose of sharing this information is to gain compliance through group pressure (Kennedy, 1997). The group/gang structure is believed to serve both as a communication vehicle, and a potential source of control, as the threat of group-focused enforcement encourages groups to police themselves (Tillyer & Kennedy, 2008). Additional messages regarding the availability of assistance, social services, and job opportunities are often conveyed. Finally, most meetings include some form of community messaging that describes the harm inflicted by violence to individual victims and the larger community, along with a plea to change their behavior. This type of “community moral voice” is designed to send clear messages of non-violence, and rejecting norms that promote violence (Brunson, 2015). Offender notification sessions are designed to alert offenders and alter their decision-making by conveying possible sanctions while offering available services, contingent upon the path that the offender (typically on probation and/or parole) chooses, be it desistence or continued high-risk behavior. Initiatives built on call in sessions ultimately seek to change offender behavior by blending law enforcement, community mobilization, and social service provisions in a targeted and directed fashion. While initiatives such as focused deterrence strategies, which rely heavily on offender notification sessions, have often corresponded with reductions in citywide gun violence and gang homicides, the direct influence of call in sessions on individual-level behavior (for those called-in) is far less understood. The following study examines the impact of offender notification meetings – with messaging heavily focused on compassion, support, and the harm inflicted by violence – on the likelihood of offender recidivism in Las Vegas, Nevada. Officials from the Las Vegas Metropolitan Police Department (LVMPD) and the Nevada Department of Public Safety, Division of Parole and Probation (NPP) worked collaboratively to conduct a series of offender notification meetings. Other components that typically accompany the implementation of focused deterrence strategies (e.g. targeted gang enforcement and social services provision) however, were not systematically implemented. Therefore, the following research represents a test solely of the impact of the offender notification meetings, answering the question of whether this form of communication with offenders has an impact on their individual likelihood of recidivism. In order to better understand the influence of call in sessions on offender recidivism patterns, officials from LVMPD partnered with researchers from the International Association of Chiefs of Police (IACP) / University of Cincinnati (UC) Center for Police Research and Policy, along with academic partners from the University of Nevada Las Vegas (UNLV) to randomize and implement an experimental trial to assess the impact of call in sessions on probationers and parolees in Las Vegas in the Spring and Fall of 2018. Using a randomized controlled trial (RCT) research design, this study addresses the following specific research questions:

1) What impact does attendance of probationers/parolees at offender notification meetings have on individual likelihood of recidivism? 2) Can a simple risk classification be developed using offender criminal histories and associations with violent gangs to assess whether risk classification correlates with offender recidivism patterns? 3) Does the impact of offender notification meetings vary based on probationer/parolees’ risk classification? Within the randomization component, probationers/parolees were first stratified into one of four possible categories dependent upon their prior violent criminal histories and current affiliation with a violent criminal gang in Las Vegas: 1) Low-Risk (neither a violent criminal history nor affiliated with a violent gang), 2) Low/Moderate-Risk (no prior violent criminal history but affiliation with a violent gang), 3) Moderate-Risk (prior violent criminal history but no affiliation with a violent gang), and 4) High-Risk (both violent criminal history and affiliation with a violent gang). A random case-control selection occurred within each risk-level stratum, and various waves of probationers and parolees who were assigned to treatment were called-in to attend notification sessions in May 2018 and October 2018. In total, 216 probationer/parolees were randomly assigned to treatment, and 300 to control groups. Probationer/parolee recidivism is the primary outcome of interest, operationalized in two forms: 1) a re-arrest of any type, and 2) an administrative failure (revocation) of probation/parole supervised by NPP. If either event occurred in the follow-up period (i.e., 12 months for May sessions, 9 months for October sessions) – the probationer/parolee (in either treatment or control condition) is classified as having recidivated. Three analytic strategies are employed for the various strata (as well as overall treatment-tocontrol comparisons) and waves of probation/parolee participants. First, a set of bivariate chisquare analyses on recidivism patterns for each risk group to set the foundation regarding covariation in treatment assignment (and attendance) calibrated with recidivism across the risk groups and waves of participants during the study period. Second, a series of binary logistic regression models for our recidivism outcome (where yes = 1 or no = 0) for each risk group (including culling all strata into a single analysis) and each wave of probationers and parolees in the study are estimated (see Long, 1997). The use of the multivariate regression model on our dichotomous outcome of interest allows, where appropriate, to include control variables in the analyses. While the use of statistical controls in randomized controlled trials is subject to debate, where statistical controls are potentially necessary (e.g., unbalanced covariates of importance between treatment and control probationers/parolees within each strata), the multivariate regression framework (including the logistic regression model) allows for such controls to be included into a single regression estimation. Finally, a series of Cox proportional hazard models are estimated to assess the effect that randomized treatment had on individual recidivism (see Cox, 1972).

Alexandria, VA: International Association of Chiefs of Police, 2020. 49p.