Serial killers are, thankfully, quite rare in the world of criminals and most professionals with a forensic psychology degree will not have to worry about them. However, something about those murderers grips the public consciousness like nothing else. News of a serial murderer in California can send shivers up the spine of someone reading about the news while sitting in a comfortable and distant home in Maine. The reason that we fear these types of murderers is the same reason that they fascinate us. They are alien to us; their minds do not make sense to the way that normal people view the world. We want, we need, to make sense of why the monsters do the things that they do. The criminal profiler, and to some extent the forensic psychologist, often studies and helps to catch these types of criminals.
Profiling the Monsters
The aim of criminal or psychological profiling is to make it possible to learn and understand the behaviors of these types of criminals. Learning the behavior of the unknown subject can help investigators to narrow their focus when they are searching through a very large subject pool.
Very often, a serial killer is going to have a signature, and often it is something of a ritual, that he performs with the victims. The signature is not something that is usually required to commit the murder – meaning that it is not going to be the cause of death. Instead, it is going to be something that the killer does to fulfill some type of need – generally emotional, sexual, or psychological or a combination. It could be the way that the killer positions the body, or something that he leaves on or near the body. The signatures can help a psychologist to understand more about the type of person who is committing the crimes, and again this can help to narrow the pool of suspects.
Some people mistakenly confuse the MO or modus operandi with the signature, but they are different things. The MO is often the way in which someone commits a crime. Such as the person always uses a knife to kill the victims, or that the killer chooses a certain type of victim on each outing. Part of the MO could be the location of the crime too. Over time, the MO can change. The dynamic MO evolves, often as the killer gains more competence. The cuts might be similar to those found in the first victim. However, they may show more precision and less hesitation, as the murders continue.
The signature is similar to ritual, and it is different from the method by which they commit the crimes. It is important to remember this.
A Fictional Example
Let’s take an example of a fictional serial killer to see the differences between MO and signature.
For this example, let’s say that the killer only targets men the ages of 20 and 50, and all of the victims, murdered over the course of the past two years, were killed with knives. The bodies were discovered near a river, park or rural area. This is the MO of the killer, and it can be useful in linking crimes together.
In addition, each of the bodies has a single shallow cut along the sternum as well as mutilated genitals. The bodies all have blindfold on them, and all of the bodies are in sexually explicit positions. This is the signature.
Both of these things can be quite useful in profiling. Looking into the backgrounds of the fictional case, a psychologist or investigator might discover that all of the men – from different lifestyles – had one thing in common. They were all registered sex offenders. This can help investigators who are looking for the killer.
Of course, the above is a simplified version of what real investigators and profilers will have to deal with in the field. Things will not be so easy to notice most of the time, so it takes a trained eye. While most people who have a forensic psychology degree will never have to be involved in a case involving a serial killer, they are interesting cases to learn about and ponder.