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Forensics: Profiling the Perpetrator

If you don't know what you're looking for, finding it is nearly impossible. Profiling, or looking at evidence and making a best guess as to the type of individual who would commit the crime in question, helps investigators get a firm grasp on whom it is they're trying to track down. The profiler, usually a specially trained FBI agent,looks at the crime scene, autopsy data, victim, and likely precrime and postcrime behaviors of the killer to make this assessment. The profiler answers questions like:

  • How did the killer gain access to the victim?
  • What did the killer do to the victim?
  • Did the killer try to cover his or her tracks and, if so, how?
  • What is it about this victim that attracted the killer?
  • What motive or fantasy drove the killer to harm the victim in the particular manner at the particular time and location?

In serial murder cases, offenders often are termed unknown subjects, or unsubs for short. Analysis of the crime scene may offer clues to the type of unsub police should search for. That analysis has become known as offender profiling. Even though profiling may not lead to the exact individual, it often helps police narrow the focus of their investigation. In addition to predicting where other evidence is likely to be located, profiling may suggest the unsub's

  • Physical and psychological makeup
  • Areas of residence and work
  • Behaviors that may have been exhibited before the crime
  • Likely comings and goings after the crime

Lastly, the crime scene may reveal aspects of an unsub's modus operandi (MO, or method of operation) and signature. Check out the later section about "Distinguishing MO from signature."

Criminal profiling evolved from studies conducted by the FBI's Behavioral Science Unit, which now is known as the Investigative Support Unit. The studies were designed to gain insight into violent criminals. As investigators' collective understanding of violent offenders increased, a useful investigative tool was born. Crime-scene analysis for clues to the offender's personality and motives and offender profiling continually gained popularity and now are considered critically important in tracking serial offenders. The premise that the perpetrator not only leaves behind physical evidence but also behavioral and psychiatric evidence is leading criminalists to understand that this evidence may be key to finding perpetrators.

One of the basic tenets of profiling is that behavior reflects personality. How a person acts depends upon his or her personality and psychological needs and fears. Profiling seeks clues to the perpetrator's personality from the behaviors he or she exhibits at the crime scene. These clues can provide insight into the killer's motives, level of intelligence and sophistication, and reasons for selecting a particular victim.

Assessing the perpetrator's psyche

One basic method of characterizing offenders from crime-scene evidence divides them into the following three categories:

  • Organized offenders: These criminals are more sophisticated in their approach, and their crimes show evidence of planning. These types tend to be of average or better intelligence, employed, and in active social relationships such as with spouses and families. Even though they're driven by their fantasies, they maintain enough control to avoid being impulsive. They prepare and even rehearse. They tend to target specific victims or types of victims and use control measures such as restraints to maintain victim compliance. They bring the tools they need to gain access to and control of the victim and avoid leaving behind evidence. As killers, they generally hide or dispose of the body and are likely to have a dumpsite already selected.
  • Disorganized offenders: These criminals usually live alone or with a relative, possess lower-than-average intelligence, are unemployed or work at menial jobs, and often have mental illnesses. They act impulsively, or as if they have little control over their fantasy-driven needs. They rarely use ruses to gain the victim's confidence, but rather attack with sudden violence, overwhelming the victim. The crime scene often is messy and chaotic. This type of offender doesn't plan ahead or bring tools along, but rather uses whatever is handy. As killers, they typically leave the body at the scene and exert little effort to avoid leaving behind evidence. Some have sexual contact with the victim after killing him or her.
  • Mixed offenders: Some offenders leave behind mixed messages at crime scenes. They show evidence of planning and a sophisticated MO, but the assault itself may be frenzied or messy, which may indicate some control over deep-seated and violent fantasies.

Profilers have developed categories of descriptors, or ways that they describe the types of individuals who commit the crimes. Some of the descriptors used in serial killer profiling are as follows:

  • Age: Most serial killers are in their 20s or 30s.
  • Sex: Almost all are male.
  • Race: Most don't cross racial lines. That means, in general, White offenders kill Whites, while Black offenders kill Blacks.
  • Residency: Organized offenders may be married, have a family, and be well liked by their friends. Disorganized offenders, because of their mental instability and immaturity, tend to live alone or with a family member.
  • Proximity: The location of the perpetrator's home in relationship to the crime scene is important. Most kill close to home, a factor that is particularly true with the first few victims. The area close to home is a comfort zone. With experience, however, the killer may move his predatory boundaries farther and farther from home.
  • Social skills: Killers who use a ruse to ensnare their victims, like Ted Bundy did, typically possess good social skills, whereas those who use a blitz-style attack are less comfortable with conversation.
  • Work and military histories: Organized offenders more often have a stable work history and are more likely to have left any military service with an honorable discharge. Disorganized offenders often are quite simply too unstable to hold a job in the long term or to complete military service.
  • Educational level: Organized offenders tend to have more schooling than their disorganized counterparts.

Using these descriptors, profilers can create a pretty good picture, or profile, of the type of person who likely committed the crime. This profile may help police home in on a specific suspect and may play an important role during the interrogation of suspects. Knowing the type of individual who'd commit a criminal act helps investigators design the right questions and leverage any pressure points during interrogation that snare suspects in a web of lies or even produce a confession.

Profiling also plays an important role in determining whether a crime scene is staged. Staging means changing the appearance of the scene so that it looks like the murder took place in a different manner and for a different reason. A classic example: the husband who kills his wife in a fit of anger, then empties drawers and closets, knocks over furniture, and breaks a door lock or window to make it appear as though a burglar committed the crime. When investigators discover that the wife was severely bludgeoned and stabbed 20 times, the light of suspicion falls on the husband. A burglar wouldn't engage in such overkill, preferring instead to kill and run. Overkill usually is personal, with anger as the common underlying drive.

Taking trophies and souvenirs

Many criminals take things from the crime scene. Money, jewels, electronic equipment, and other valuables that can be sold commonly are taken, as is incriminating evidence, such as the murder weapon or a used condom.

Serial offenders, on the other hand, tend to take objects that have no monetary or evidentiary value. But, regardless of what the object is, it holds some value to the perpetrator, and he will use it to relive the crime in later fantasies. Some killers take jewelry, clothing, even driver's licenses. Some take body parts.

Distinguishing MO from signature

Modus operandi (MO, or method of operation) describes the tools and strategies a criminal uses to commit a crime and isn't a new concept. It dates back to the 1880s and the efforts of Major L. W. Atcherley, a police constable in the West Riding Yorkshire Constabulary in England, who developed a 10-point system for identifying a perpetrator's MO. Scotland Yard later adopted many of his techniques.

Atcherley considered the following factors:

  • Location of the crime
  • Point of entry
  • Method of entry
  • Tools that were used during the crime
  • Types of objects taken from the crime scene
  • Time of day the crime was committed
  • The perpetrator's alibi
  • The perpetrator's accomplices
  • Method of transportation to and from the scene
  • Unusual features of the crime, such as killing the family dog or leaving behind a note or object to taunt the police

All these factors address the perpetrator's method of doing things. They are the things that he or she sees as necessary to committing — and getting away with — the crime.

An MO may evolve over time as the unsub finds better ways to commit the murders or other crimes, perhaps changing his mode of entry, ruse, disguise, or when the attacks take place — whatever makes the unsub's efforts more effective and helps him avoid detection.

In contrast to an MO, a signature is an act that has nothing to do with completing the crime or getting away with it. Signatures are important to the offender in some personal way. Torturing the victim, overkill, postmortem mutilation or posing, and the taking of souvenirs or trophies are signatures. These actions are driven by the killer's psychological needs and fantasies.

Unlike an MO, a signature never changes. It may be refined over time, but the basic signature remains the same. For example, if a serial killer poses victims in a religious manner, praying or as a crucifix, details such as candles, crucifixes, or other ceremonial objects may be added later. The signature has changed, but its basic form and theme remain the same.

The reason for the stability of the signature lies in its driving force. The signature is derived directly from the unsub's fantasies. These fantasies develop early in life and are refined into an obsession from years of mental reenactment. During the crime, an unsub forces the victim to respond according to the script from his fantasy. The signature is solely for the killer to live out his personal fantasy. Because the fantasy never changes, the signature remains intact.

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