By John E. Douglas, Ed.D. Special Agent
Chief of the Investigative Support Unit FBI Academy
and
Corinne Munn
Served as Honors Intern FBI Academy
This Article Originally Appeared in the FBI Law Enforcement Bulletin, February 1992.
Most crime scenes tell a story. And like most stories, crime scenes have
characters, a plot, a beginning, a middle, and hopefully, a conclusion. However,
in contrast to authors who lead their readers to a predetermined ending,
the final disposition of a crime scene depends on the investigators assigned
to the case. The investigators’ abilities to analyze the crime scene and
to determine the who, what, how, and why govern how the crime scene story
unfolds.
To ensure a satisfactory ending, that is, the apprehension and prosecution
of the violent crime offender, investigators must realize that the outcome
depends on their insight into the dynamics of human behavior. Speech patterns,
writing styles, verbal and nonverbal gestures, and other traits and patterns
give shape to human behavior. These individual characteristics work in concert
to cause each person to act, react, function, or perform in a unique and
specific way. This individualistic behavior usually remains consistent,
regardless of the activity being performed.
Since the commission of a violent crime involves all the dynamics of “normal”
human behavior, learning to recognize crime scene manifestations of behavioral
patterns enables investigators to discover much about the offender. It also
provides a means by which investigators can distinguish between different
offenders committing the same types of offense.
There are three possible manifestations of offender behavior at a crime
scene–modus operandi, personation or signature, and staging. This article
addresses each of these manifestations in order to demonstrate the importance
of analyzing a crime scene in terms of human behavior.
Modus Operandi
In 1989, Nathaniel Code, Jr., a Shreveport, Louisiana, man, was convicted
of murder. The jury determined that on three separate occasions between 1984
and 1987, Code murdered a total of eight people. The jury returned a guilty
verdict, even though several disparities existed among the three crime scenes.
For example, the offender gagged the first victim with a piece of material
obtained at the crime scene, but brought duct tape to use on the seven victims
in the other two incidents. Also, the killer stabbed and slashed the first
victim, whereas the victims of the other two crimes were also shot and showed
signs of ligature strangulation. The victims ranged in age from 8 years to
74 years and included both sexes; however, all were black. And, the offender
took money from one crime scene, but not the other two.
Considering the evidence found at the three crime scenes, could one man be
linked to all of the murders? Wouldn’t such differences in modus operandi
(M.O.), which is the offender’s actions while committing the crime, and
victimology (characteristics of the victims) eliminate the connection to
one offender?
When attempting to link cases, the M.O. has great significance. A critical
step in crime scene analysis is the resulting correlation that connects cases
due to similarities in M.O. But, what causes an offender to use a certain
M.O.? What circumstances shape the M.O.? Is the M.O. static or dynamic?
Unfortunately, investigators make a serious error by placing too much
significance on the M.O. when linking crimes. For example, a novice burglar
shatters a locked basement window to gain access to a house. Fearing that
the sound of a window breaking will attract attention, he rushes in his search
for valuables. Later, during subsequent crimes, he brings tools to force
open locks, which will minimize the noise. This allows him more time to commit
the crimes and to obtain a more profitable haul.
As shown, the burglar refined his breaking-and-entering techniques to lower
the risk of apprehension and to increase profits. This demonstrates that
the M.O. is a learned behavior that is dynamic and malleable. Developed over
time, the M.O. continuously evolves as offenders gain experience and confidence.
Incarceration usually impacts on the future M.O.s of offenders, especially
career criminals. Offenders refine their M.O.s as they learn from the mistakes
that lead to their arrests.
The victim’s response also significantly influences the evolution of the
M.O. If a rapist has problems controlling a victim, he will modify the M.O.
to accommodate resistance. He may use duct tape, other ligatures, or a weapon
on the victim. Or, he may blitz the victim and immediately incapacitate her.
If such measures are ineffective, he may resort to greater violence or he
may kill the victim. Thus, offenders continually reshape their M.O. to meet
the demands of the crime.