The available research, although sparse, indicates that the type of homicide has a bearing on whether it is cleared by arrest. As easily cleared homicides (family-related) decline, a greater proportion of homicides that are more difficult to clear (felony homicides) remain. Consequently, the use of arrest clearances as a measure of police performance, insofar as it attempts to measure the efforts of individual officers, is misplaced, because it fails to take into account the difficulty of clearing certain types of homicides compared to other types. There is much evidence to suggest that low-status citizens do not receive as many benefits from law as high-status citizens. Police vacillate between hostility and indifference in dealing with the conflicts of low-status citizens. Common street conflicts, such as robbery homicides involving drugs, do not receive as much investigative attention as cases that involve socially defined "vulnerable" victims. The variables of community and third-party cooperation with police in homicide investigations constitute another significant factor that determines the outcome of homicide investigations. In high-crime neighborhoods, third-party witnesses are concerned about retaliation and are often fearful that they might become homicide victims. Further, in cases in which the victims are socially isolated, e.g., prostitutes, the homeless, and the elderly who live alone, there is little incentive for third-party strangers to the victim to cooperate with the police in providing evidence. Overall, the most important policy implication of these findings is that arrest clearances are an inadequate measure of the effectiveness of police performance in homicide investigations. This measure fails to take into account the proportion of felony homicides, whether the homicides are gang or drug-related, and whether investigating officers face a hostile and uncooperative community. 2 figures, 2 tables, and 45 references