Evaluation of the Phoenix, Arizona, Homicide Clearance Initiative, 2003-2005

The purpose of the study was to conduct a process and outcome evaluation of the Homicide Clearance Project in the Phoenix, Arizona Police Department. The primary objective of the Homicide Clearance Project was to improve homicide clearance rates by increasing investigative time through the transfer of four crime scene specialists to the homicide unit. In 2004, the Phoenix Police Department received a grant from the Bureau of Justice Assistance providing support for the assignment of four crime scene specialists directly to the department's Homicide Unit. Responsibilities of the crime scene specialists were to collect evidence at homicide scenes, prepare scene reports, develop scene diagrams, and other supportive activities. Prior to the project, homicide investigators were responsible for evidence collection, which reduced the time they could devote to investigations. The crime scene specialists were assigned to two of the four investigative squads within the homicide unit. This organizational arrangement provided for a performance evaluation of the squads with crime scene specialists (experimental squads) against the performance of the other squads (comparison squads). During the course of the evaluation, research staff coded information from all homicides that occurred during the 12-month period prior to the transfers (July 1, 2003 - June 30, 2004), referred to as the baseline period, the 2-month training period (July 1, 2004 - August 31, 2004), and a 10-month test period (September 1, 2004 - June 30, 2005). Data were collected on 404 homicide cases (Part 1), 532 homicide victims and survivors (Part 2), and 3,338 records of evidence collected at homicide scenes (Part 3). The two primary sources of information for the evaluation were investigative reports from the department's records management system, called the Police Automated Computer Entry (PACE) system, and crime laboratory reports from the crime laboratory's Laboratory Information Management System (LIMS). Part 1, Part 2, and Part 3 each contain variables that measure squad type, time period, and whether six general categories of evidence were collected. Part 1 contains a total of 18 variables including number of investigators, number of patrol officers at the scene, number of witnesses, number of crime scene specialists at the scene, number of investigators collecting evidence at the scene, total number of evidence collectors, whether the case was open or closed, type of arrest, and whether the case was open or closed by arrest. Part 2 contains a total of 37 variables including victim characteristics and motives. Other variables in Part 2 include an instrumental/expressive homicide indicator, whether the case was open or closed, type of arrest, whether the case was open or closed by arrest, number of investigators, number of patrol officers at the scene, number of witnesses, and investigative time to closure. Part 3 contains a total of 46 variables including primary/secondary scene indicator, scene type, number of pieces of evidence, total time at the scene, and number of photos taken. Part 3 also includes variables that measure whether 16 specific types of evidence were found and the number of items of evidence that were collected for 13 specific evidence types.