Method of Operation (M.O.)

The concept of method of operation (M.O.) or modus operandi, as it has been historically termed, is a means of identifying a single perpetrator in a series of criminal events. Forensic evidence such as crime scene photographs, physical evidence , autopsy photographs and report, and an extremely detailed study of the characteristics of the criminal's behavior is compiled. Methodology, weapons, means of victim acquisition, location of crime, victim demographics, methods and types of ligatures or bindings, and crime-scene characteristics are also compiled and analyzed in order to create a picture of the unique perpetrator, as well as to link geographically or temporally remote crimes that were previously believed to be unrelated, but that actually encompass a serial pattern.

The offender's method of operation undergoes an evolutionary process, one that changes as he or she becomes more skilled at committing a particular act (or a series thereof). That is, the perpetrator learns to be more successful at achieving his or her particular aim in the commission of the crime over time (with practice, skills improve). Another aspect of the M.O. is referred to as the signature, consisting of those behaviors emitted but not actually required in the commission of the crime. Signature behaviors are suggestive of the personality of the offender and help to distinguish similar or copycat offenses. Some examples of signature behaviors are use of specific ligature or binding materials, type and order of knots used, repeated unusual injuries such as laceration pattern, bites, disfiguration, mutilation, amputation of specific regions, evidence of torture or sadistic injuries, location and type of crime scene, victim posture, body arrangement, and actual messages left at the crime scene or divulged to the media.

The study of criminal method of operation offers the forensic investigator a window into the psyche of the perpetrator; it is a means of identifying or characterizing a criminal by his or her behavior, motivation for commission of particular acts, victim choice, and crime scene characteristics. By diligent development of the specific perpetrator's M.O., it is possible to link crimes committed in different parts of the country (or the world), across time and across venues. Because people have become progressively more able to move rapidly from place to place, it is possible for a single perpetrator to commit crimes in multiple areas within short periods of time. Successful analysis and identification of an individual's M.O. can facilitate rapid identification of an offender, and markedly increase ease or rapidity of apprehension.

see also Antemortem injuries; Autopsy; Bite analysis; Body marks; Cold case; Criminal profiling; Physical evidence; Psychological profile.