The study found no significant statistical impact of mayoral election years on murder clearance rates. Neither was there a significant statistical impact on murder clearance rates associated with murder offense rates, total population of the city, State unemployment rate, police expenditures per 1,000 city population, and number of officers per 1,000 residents. This contrasted with the findings of the case study of one city, which found that investigative decisions as well as police practices and procedures in murder cases, along with murder clearance rates were influenced by media coverage, local political figures, and prosecuting attorneys. The case study challenges the assumption that police departments always act to maximize their performance; instead, they often respond to expectations and positions of the institutional supporting environment. Continued review of the political environment's influence on police practices and procedures over an extended period of time will provide more evidence of the actual influence on police performance in clearing homicides. Quantitative models were derived by regressing murder clearance rates in the 59 cities on the following variables: murder offense rate, total population of the city, State unemployment rate, police expenditures per 1,000 city population, number of officers per 1,000 residents, and a dummy variable for mayoral election year. The quantitative model also included 58 dummy variables in order to account for unobserved cross-sectional city-specific effects. Data for the case study for one city came from documents, field observation, and interviews. 2 tables, 9 notes, and 62 references