Artigo: M.O. vs Signature Aspects of a Crime Scene

Generally, the term modus operandi (M.O.) represents the functional components which are necessary for an offender to be successful in committing a crime (Keppel, 1997; Douglas et al. 1992). Historically, M.O. has been used to link cases because offenders will use similar methods during the commission of their crimes. M.O. can include factors such as; a time of day or location an offender chooses to strike, the type of victim, points or techniques for gaining entry, as well as tools used for committing the crime. However, M.O. can change over time as offenders become more experienced or learn new techniques that will make them more successful or lower their chances of being identified. For example, an offender may always strike at night, gaining entry to the location by using a glasscutter and shooting a victim. This can completely change however, if the offender learns that using a suction cup with the glasscutter and a knife to kill the victim will create less noise. Again, everything mentioned above are factors that are necessary to commit the crime. Signature aspects on the other hand, are behaviors that go beyond what is necessary to commit the crime and fulfill a psychological need of the offender. Unlike M.O., signature aspects are stable over time and will be witnessed at each crime scene throughout a series. Although there may be subtle differences from crime to crime, there will be an evident theme. As this theme represents a psychological need of the offender, signature seems to be based heavily upon, and reflect the offender's fantasies. Signature aspects are symbolic and hold special significance to the offender, and may not be understood by anyone other than the offender. If over a series of murders the victim's arms are left crossed upon their chests, this is significant to the offender and goes beyond what is necessary to commit the crime. The actual reason or meaning may not be understood by investigators, but there is a clear indication that each of these crimes were committed by the same offender for whom the crossing of the arms does have significance.I would like to begin a section here to list signature aspects that our visitors have some across while reading about or researching the topic. If you have others to add to this list, please e-mail me and I will post them here.Signature ExamplesAn offender forced a victim to call her husband and ask that he come home for some reason. When the husband arrived, he was tied to a chair and forced to watch as the offender raped his wife. (Douglas et al., 1992)ReferencesDouglas, J.E., Burgess, A.W., Burgess, A.G., & Ressler, R.K. (1992). Crime classification manual: A standard system for investigating and classifying violent crimes. San Francisco, CA: Jossey-Bass. Keppel, R.D., & Birnes, W.J. (1997). Signature killers: Interpreting the calling cards of the serial murderer. New York, NY: Pocket Books.