Classifying homicide offenders and predicting their characteristics from crime scene behavior.

A theoretical distinction between instrumental and expressive aggression was used in analyzing offender characteristics and their associations with crime scene actions in Finnish homicides. Twenty-one variables reflecting the offenders' criminal activity, previous relationships with intimates and victims, and general social and psychological adjustment were derived from files of single-offender/single-victim homicides occurring between 1980 and 1994 (n = 502). Additionally, three variables describing post-offense actions and police interview behavior were included. A multidimensional scaling procedure was used to investigate the interrelationships between the variables. A distinction between expressive and instrumental characteristics was observable in the empirical structure, which was divided into three subthemes of Instrumental, Expressive: Blood, and Expressive: Intimate. Associations between the characteristics with five previously identified subthemes of crime scene actions were computed. In addition, the subthemes of crime scene actions were related to post-offense actions and police interview behavior, with Expressive themes being associated with less denial as well as a greater likelihood of surrendering and confession. The practical usefulness for police investigations and theoretical implications of the results are discussed.