If you are going to have any aspect of a serial offender in your next great novel, you must know the very important distinction between modus operandi and signature. I’ve read quite a few books where the author has used them either incorrectly or reversed, so let’s set the record straight. This way, you can write it right – and gain credibility amongst your soon to be millions of adoring fans.
Criminal profiling involves studying criminal behavioral in detail. A behavioral assessment is done of the interaction between the victim and offender. Key questions a criminal profilers asks: Why this victim? Why this day? Why this location? Why this behavior? Behavior is what one does and how one does it. It can be similar to everyday, ordinary behaviors, but it can also be unique to the individual in question. We all have routine behaviors. Maybe walking our dog at a certain time each morning. Going to the gym for a workout. Where we get our favorite coffee on the way to work.
These are all general behaviors, because millions of people do them; however the exact times and places we walk our dog, go to the gym, and get our coffee makes our behavior more unique.
We also have fantasies about certain things, not always sexual. Perhaps owning a Ferrari, or being the CEO of a huge company, or living on Fiji in an overwater cottage. Maybe even writing a best-selling novel. These are normal fantasies.
From the offender’s point of view, much of what they do when they are committing crime is acting normally. To them, they are acting out on needs, fantasies and patterns developed over their life course, some of which may be abnormal. The crime scene contains many manifestations of these behaviors, needs, and patterns. If there are repeated crime scenes (i.e., a serial offender), it is much more likely, with proper examination, and that any unique behaviors, needs, and patterns will be uncovered. This helps criminal profilers in creating a profile to assist law enforcement in capturing the serial offender. Three elements can link crimes in a series: the method of operation (modus operandi), ritual (signs of fantasy or psychological need), and signature (unique combinations of behaviors).
MODUS OPERANDI, also referred to as M.O., is the behavior necessary for the successful commission of a crime. At a minimum, every M.O. will contain elements that: (1) ensure success of the crime; (2) protect identity; and (3) effect escape. You cannot always link cases by M.O. because it is dynamic and always changing. It’s a learned behavior like any other behavior, and involves things like experience, education, and maturity.
Some examples of M.O. are a burglar who knocks on the from door with a clipboard pretending to be a salesman, and after no answer goes around the rear and enters through a door or window; a ruse used on a person in a parking lot to get them to help them load groceries in their car, then they are pushed into the car and assaulted; identity thieves placing phone calls to a person informing them they won a prize, and need to give some personal identification to verify they are the winner, etc.
As long as this M.O. works, the criminal continues to use it. If it is not successful, they will adapt and change until they get it right. Getting arrested is great for enhancing a criminal’s M.O., for while in prison he is surrounded by other “scholars” all too willing to education him in advancing his career.
A criminal will also change his M.O. if the media publicizes their actions, their physical description, or area of the crimes. SIGNATURE In general, signature is a combination of behaviors. It is not necessary to commit the crime, but more a manifest of a sexual or psychological need to mentally abuse the victim.
In the movie “Home Alone” the thieves constantly trying to break into Macaulay Culkin’s home were nicknamed “The Wet Bandits” because after they burglarized a home, they turned all the faucets on. This is an excellent example of signature. Turning the faucets on was not necessary to burglarize the home, it was just their fantasy of knowing that when the victims came home their house would be flooded. Some criminals have quite unique signatures; defecating on the beds or the kitchen/dining room table; eating food out of the refrigerator and leaving it out, or taking undergarments out and leaving them on the floor (thus ensuring the victims knew their food or undergarments were touched).
SIGNATURE is not, however, the same thing as unusual behavior. Signatures usually put the offender at great risk because they must stay at the crime scene longer. At other times, you’ll have a combination of M.O. and signature. For example, when staging involves purposeful alteration of the crime scene in order to redirect investigation away from the offender, such as a sex offender making his crime to appear to be a robbery, or arson. Signature often involves “red flags” or inconsistencies that just do not add up to the evidence found at the crime scene or autopsy.
The signature is sometimes called a “trademark” or “calling card” and reflects a compulsion on the part of criminals to go beyond just committing the crime to “express themselves” in some way that reflects their personality (not their whole personality in some psychological sense, but something about the addictive, repetitive, or compulsion-oriented part of their personality). The core of a signature will never change, although it may get worse and worse over time (e.g., mutilation of the victim may increase from victim to victim). Signature makes criminals unique in that many may have the same M.O., but few have the same signature in conjunction with that M.O.
In your works, why not have a serial killer who pops the rear patio door off the tracks at night, murders his victims by manual strangulation, and before leaving turns the television on to his favorite police crime scene show.
