A 1992 paper by the FBI, "Killed in the Line of Duty," was based on an analysis of 51 incidents that occurred between 1975 and 1985 in which 50 offenders murdered 54 police officers in the United States. The FBI attempted to explore three key factors associated with the murder of police officers: offender, police officer, and incident. Based on data from the 50 offenders, the FBI concluded that two primary personality types -- antisocial and dependent -- were most prominent in the murder of police officers. Police officer victims were generally described as laid back, hard working, friendly, liked by the community, and reluctant to follow all the rules. The FBI also determined that only 2 of the 54 murdered police officers made no mistakes when dealing with their eventual murderer. The literature on police homicides is reviewed to put FBI findings in perspective and to identify certain problems with the FBI's methods. These problems concern sampling and data collection techniques and data biases. The FBI claim that many police officer victims committed errors and FBI recommendations on how to reduce police homicides, such as increased police officer training, are questioned. Future avenues of research on police homicides are suggested. 30 references, 1 note, and 3 tables