The main findings indicate that, first of all, police murder rates are characterized by two distinct historical periods (1947 to 1971 and 1972 to 1998) in which the structural correlates vary. Correlates of police murder from 1947 to 1971 were unemployment, inflation, and lagged executions. Correlates of police murder from 1972 to 1998 were changes in inequalities, unemployment, inflation, and alcohol. It is argued that the declining police murder rates in the 1970s, 1980s, and 1990s were a result of increased police training, technology, and research. Advanced trauma and emergency medical care is also noted as a contributing factor to the declining police murder rates. The second main finding of the research is that both economic deprivation and deterrence theories are useful in explaining police murder trends. No evidence was found for the usefulness of social disorganization or control theories. Data on felonious police murders in the United States during the study period were analyzed using econometric and time series regression techniques. Multivariate analyses were also conducted to examine the impact of theoretically relevant factors on police murder rates, such as levels of community inequality, family poverty, economic trends, family disruption, and population heterogeneity. Several variables shown to affect homicide rates in previous studies were controlled, including age and general murder rates. Future research should focus on identifying the organizational factors that are associated with felonious police killings. Figure, table, notes, references