Evaluation of the Phoenix, Arizona, Homicide Clearance Initiative

Project Summary Abstract

Research Goals and Objectives:

Statement of Purpose. There is a substantial amount of literature on the procedural aspects of criminal investigations but few studies on those factors that contribute to the successful closing of a homicide case. There are various solvability factors that may be considered in the course of investigation including collection and preservation of physical evidence and investigative techniques such as canvassing a scene and interviewing witnesses. To further our understanding of factors contributing to clearance rates, it is necessary to study the effects evidence collection personnel and detective activities on solving a case.

The proposed evaluation will examine the effects evidence technicians have on homicide clearance rates in the Phoenix Police Department. The study will also look at the effects that proven solvability factors such as number of detectives assigned to a case, witness statements, and computer queries of victims and offenders have on the closing of a case.

Proposed Research Design & Methodology:

Methods. The study will employ a quasi-experimental design whereby homicide squads will be assigned to a target and comparison group. There will be a pre-period where homicide investigators will be responsible for all investigative work including evidence collection. The target group will be given the intervention (evidence technicians.) The grantee will compare the activities of the target and comparison groups after the intervention period to determine the effects of evidence technician on clearance rates. The homicide case review database will be analyzed using bivariate and multiple regression methods, which will allow for a comparison of the clearance rates of the target and comparison squads. Additional statistical analyses will be performed.