This report brings together in a single publication national statistics on two distinct types of homicide: the justifiable homicide of felons by police, and the murder of police officers by felons.Although the two are fundamentally different - the use of deadly force against a police officer is almost never justified, while the use of deadly force by police often is - certain connectionscan be made between them beyond the fact that both always involve the police. Sometimes one directly results in the other: 1 in 6 murders of a police officer result in the justifiable killing of themurderer. (Still, of all the justifiable homicides by police only about 3% occur in connection with the murder of a police officer.) The two also sharedemographic similarities. For example, almost all the felons justifiably killed by police (98%) and almost all of the felons who murdered a police officer (97%) are males; in both types of homicidejust over half of the felons are ages 18 to 30; and in both types just over half of the felons are white.The first section of the report deals with the justifiable homicide of felons by police; the second, with the murder of police officers by felons. Together, the two types account for around 2% of all intentional killings in the United States.The types of homicide not covered in this report are: negligent homicides; justifiable homicides by private citizens; and murders in which the victim issomeone other than an officer slain in the line of duty.