The Influence of Investigative Resources on Homicide Clearances

ObjectivesThis paper investigates the influence of case characteristics and investigative resources on homicide clearance rates.MethodsWe extend a previous evaluation of a problem-oriented policing project intended to improve homicide clearance rates in Boston. Data were collected on N=465 homicide incidents that occurred between January 1, 2007 and December 31, 2014. Confirmatory factor analyses are used to identify latent variables representing investigative resources, initial crime scene results, and subsequent investigative actions and forensic testing. The effects of these investigative factors on homicide clearances net other covariates were estimated using mixed effects logistic regression models. Mediation analysis was then used to decompose the total, direct, and indirect effect of investigative resources on homicide clearances. Exploratory group comparisons were examined to distinguish investigative differences in gang and drug homicides relative to non-gang and non-drug homicides.ResultsInvestigative resources, crime scene results, and subsequent investigative actions and forensic testing were found to increase the likelihood of homicide case clearance controlling for other covariates. Investigative resources were found to produce both direct and indirect impacts on homicide clearances mediated through its positive influence on initial crime scene results and subsequent investigative actions and forensic testing. Clearance through follow-up investigation was more difficult for gang and drug homicide cases when compared to other homicide cases.ConclusionWhile inherited case characteristics matter, enhanced investigative resources and improved practices increase homicide clearances. Beyond investments to improve investigations, gang and drug homicides remain particularly difficult to clear due to a lack of physical evidence and witness cooperation.