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Modus Operandi Vs. Offender Signature

Noor Z. Razzaq

Many aspects of forensic psychology (behavior analysis) are used to identify suspect(s) of violent crime in modern police investigations. The two most basic aspects of measurable and identifiable criminal behavior in the field of forensic behavioral analysis are modus operandi (MO) and offender signature. In order to perform effective investigations of violent or serial crime, investigators should have a rudimentary understanding of these basic profiling concepts beyond the realm of common usage, or rather misuse. This article will focus on the characteristics and differences between modus operandi and offender signature and why this understanding can be integral to violent crime investigations.

All criminals have a MODUS OPERANDI consisting of techniques, habits, and peculiarities in behavior which are performed with three basic objectives (Turvey, 2002):

1. Complete the crime

2. Affect escape

3. Avoid capture (e.g., investigation)

Serial offenders modify and perfect their MO as they become more adept at what they do. The improvement or slight adjustment to an offender’s MO is something for investigators to bear in mind in analyzing a criminal pattern over time and formulating a behavioral profile. This is especially true in the first stages of profiling when the investigator begins his or her profile from the paradigm of the Organized/Disorganized continuum. While offender MO pertains to the methods used to commit a crime, offender signature has a much less pragmatic role for the perpetrator.

OFFENDER SIGNATURE can be broken down into two separate but interdependent halves: signature aspect and signature behavior. Signature aspect defines the theme or motive of an offense, and can include motivational categories such as profit, anger, retaliation, assertiveness, sadism, and et cetera (Turvey, 2002). Signature behaviors, on the other hand, are committed to satisfy the emotional and psychological needs of the offender and usually define the theme of a crime.

The common challenge in distinguishing the MO from offender signature lies in the fact that certain offender actions committed in the act of the offense may satisfy both the offender’s MO and his or her signature. The key to determining which behavior falls into what category lies in the totality of the circumstances surrounding the offense. An example would be a rapist who covers his face. The act in and of itself could be an MO behavior in that the rapist may be attempting to conceal his identity. It could also be classified as offender signature in that covering his face enhances the sexual pleasure he may derive from the rape scenario in itself.

However, in profiling a burglar or bank robber who covers his face with a mask, the investigator could assume the action to be primarily MO due to the fact concealment of identity is integral to the completion of the crime without being caught. Differentiating between MO and offender behavior in other types of crimes may be a little more obvious. For example, MO behavior for an arsonist could be if he leaves his car running near a building he is about to set fire to in order to affect a quick escape. An offender signature for that arsonist would be to return to the scene of the crime and watch the havoc subsequent to the arson in order to experience pleasure, sexual or otherwise.

Although a sometimes confusing and often neglected subject, it is absolutely imperative for violent crime investigators to have a rudimentary understanding of the concepts behind ‘modus operandi’ and ‘offender signature’. The virtual impossibility of two or more offenders fitting the same modus operandi and the signature behavior(s) while operating in the same geographic area at the same time is the key to the importance of this understanding. Ultimately, it is up to the investigator to effectively analyze the totality of the circumstances surrounding the offense in order to make determinations regarding the classification of these behaviors. Once classifications are made, further profiling can be conducted allowing for one more tool to be used in further narrowing of the suspect pool and the building of a case against the offender, ultimately resulting in a quicker resolution to the investigation.


Turvey, B. (2002). Criminal Profiling: An Introduction to Behavioral Evidence Analysis (2nd Ed.). London, UK: Elsevier Academic Press.

Meyer, C.B. (2000). Introduction to Criminal Profiling. Retrieved April 9, 2007, from:

Copyright © 2008 by Noor Z. Razzaq. All rights reserved.

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