This article examines the deterrent effect of executions on first-degree murders in Chicago, Illinois for the period 1915-1921. Chicago provides an ideal research setting since there is close geographic proximity between the place where first-degree murders are committed and the place where the convicted murderers are executed. The population density factor included in the model is very highly correlated with the nonwhite population, male population fifteen to thirty-four years of age, and the foreign born population variables. In examining monthly first-degree murders and total criminal homicides, two execution measures are utilized: the actual number of monthly executions, and a dummy execution variable, where execution months are assigned a weight of one and non-execution months a weight of zero. The two sociodemographic control variables considered in the analysis are population density and percent of the city budget expended on care for the homeless and other needy adults and children. These factors are included in the analysis to control for changes in the nature of the Chicago population and socioeconomic conditions during the seven-year period. In addition, the population density variable has the effect of controlling for changes in population size since the boundaries of Chicago did not change from 1915 through 1921.