Encyclopedia of Psychology and Law

homicide is more often motivated by sexual fantasies

and desires. Having said this, the relationship between

serial murder and sexual motivation may be an artifact

of how serial murder is defined. Future researchers

must consequently avoid confounding the criteria used

to define serial murder (i.e., motivation) with the pre-

sumed motivation for serial murder by defining serial

murder using variables other than sexual motivation.

Whether sexual motivation is an artifact of how ser-

ial murder is defined, nearly half of the serial killers

who have been interviewed deny that there was a strong

sexual component to their crimes. A small portion

(4–5%) of serial murders appear to be motivated by

psychosis, and slightly more are motivated by a strong

profit motive. Revenge, on the other hand, may be a

more powerful motive for serial murder than either psy-

chosis or profit. There is preliminary evidence, for

instance, that some serial killers target victims who dis-

play characteristics symbolic of a group or person they

despise. Ted Bundy targeted young women with long

dark hair parted down the middle because these were

prominent features of a woman who had spurned him

years earlier. John Wayne Gacy preyed on young males

as a way, perhaps, of venting hatred toward his own

homosexuality. An even stronger motive for serial mur-

der is the power a person can derive from taking con-

trol of another person’s life. Forcing a stranger to

submit to their every demand and then killing the per-

son with their bare hands, a knife, or a piece of rope can

be highly reinforcing to a serial killer.

Typologies

Several typologies have been advanced in an effort to

classify serial killers into discrete categories. One of

the more popular typologies, the organized/disorga-

nized typology, was developed at the FBI’s Behavioral

Science Unit in Quantico, Virginia. The organized ser-

ial killer is said to be of average to above-average intel-

ligence, with good social skills, and a reasonably

stable employment history. The murders enacted by an

organized serial killer are usually well planned and

typically involve the use of a weapon. Such individu-

als are said to leave an organized crime scene. A dis-

organized serial killer, on the other hand, possesses

below average intelligence, weak impulse control, and

poor social skills, leading to an unplanned attack that

often results in a disorganized crime scene. The orga-

nized/disorganized typology was developed and vali-

dated on a group of 36 serial killers and other offenders

who volunteered to be interviewed by the FBI. Recent

empirical research has failed to support the orga-

nized/disorganized dichotomy, showing instead that

most serial killers are organized and that they vary

along a continuum of increased organization rather

than splitting off into two groups.

Another popular typology of serial murder was pro-

posed by Holmes and DeBurger. This typology consists

of four categories: (1) visionary type; (2) mission-

oriented type; (3) hedonistic type, which is broken

down further into the lust killer, the thrill killer, and the

creature-comfort killer; and (4) power/control type.

Separate descriptions and motives are listed for each

category in the typology. For instance, the visionary

type is alleged to be motivated by delusions and hallu-

cinations, is opportunistic in selecting victims, and

leaves a messy crime scene, whereas the hedonistic

type is motivated by personal enjoyment, pleasure, or

gain, carefully selects victims based on predetermined

criteria, and generally leaves a tidy crime scene. The

problem with the Holmes and DeBurger typology is

that because the four types are so poorly defined and

the boundaries that separate them so indistinct, there is

a high degree of overlap between types—a fatal flaw in

any typology. Furthermore, there is no empirical sup-

port for the typology either as an effective shorthand in

describing serial homicide or as a mechanism for pre-

dicting future behavior.

Future Research

Serial murder is a rare event, thereby making it difficult

to research. At present, nearly all of what we know

about serial murder is based on a few case studies con-

ducted on individuals who agreed to be interviewed by

law enforcement and a handful of archival studies using

information gleaned from newspapers, police files, and

court documents. Consequently, there is a need for

more empirical research on serial murder. First, a gen-

erally accepted definition of serial murder must be

found so that it can serve as the standard for future

research on serial homicide. The use of divergent defi-

nitions of serial murder and confounding definitions

with variables (e.g., motivation) have thus far hindered

progress in the field. Second, theoretical models, such

as Hickey’s Trauma-Control Model, need to be created,

tested, and refined. A good theory could reap tremen-

dous benefits by advancing research and practice in the

field. Third, alternatives to the traditional serial killer

typologies need to be found. One such alternative is the

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