Linkage analysis: Modus operandi, ritual, and signature in
serial sexual crime
Robert R. Hazelwood
, Janet I. Warren
Academy Group, Manassas, VA, USA
Institute of Law, Psychiatry, and Public Policy, University of Virginia, 1107 West Main Street,
Charlottesville, VA 22903, USA
Received 24 June 2002; accepted 29 July 2002
This article examines a process of behavioral analysis, referred to as linkage analysis, used in
identifying sexual offenses that have been committed by the same offender. This type of analysis
examines behavior that is contained in three distinct components of a crime, i.e., the modus operandi
(MO) or the ‘‘how to’’ of a crime; the ritual or fantasy-based behaviors for a particular type or series of
sexual crimes; the signature or unique combination of behaviors, which suggests that a series of crimes
has been perpetrated by the same offender. Linkage analysis involves five assessment procedures: (1)
gathering detailed, varied, and multisource documentation; (2) reviewing the documentation and
identifying significant features of each crime individually across the series; (3) classifying the
significant features of the crime as either MO and/or ritualistic constructs; (4) comparing the
combination of MO and ritualistic features across the crimes to determine if a signature exists; (5)
compiling a written analysis that details the conclusions derived from the available information.
Results of this type of analysis can be used for investigative purposes and, in some instances, can help
to inform the decision-making of the courts.
D2002 Elsevier Science Ltd. All rights reserved.
Keywords: Linkage analyses; Serial sexual crime; Ritualistic criminal behavior; Criminal investigative analyses
1359-1789/$ – see front matter D2002 Elsevier Science Ltd. All rights reserved.
* Corresponding author. Tel.: +1-434-924-8305; fax: +1-434-924-5788.
E-mail address: jiw@Virginia.EDU (J.I. Warren).
Aggression and Violent Behavior
8 (2003) 587– 598
Growing awareness of the serial nature of a significant proportion of sexual crimes has
motivated scientific and behavioral efforts to determine ways of linking crimes perpetrated by
a single offender. Increasingly, DNA analyses allow investigators and prosecutors to
scientifically determine not only the identity of the perpetrator in a single case of sexual
assault, but to ascribe responsibility to the offender, in some instances, for cases that have
occurred over long time intervals and geographically distinct locales. However, the avail-
ability of DNA evidence is only beginning to be consistently and readily obtainable. In a
significant proportion of sexual crimes, no DNA evidence is left at the scene, or what is
available for analysis is insufficient to allow for a definitive identification.
In such cases, behavioral analyses can be used to explore the likelihood that a series of
crimes have been perpetrated by the same offender. We would like to describe one specific
type of behavioral analysis, referred to as linkage analysis, which integrates information from
three distinct but interrelated aspects of a crime pattern perpetrated by a single offender. These
involve the modus operandi (MO) or the ‘‘how to’’ of a crime; the ritual or fantasy-based
behaviors for a particular type or series of sexual crimes; the signature or unique combination
of behaviors, which suggests with a high degree of probability that a series of crimes has been
perpetrated by the same offender. Linkage analysis involves five assessment procedures: (1)
gathering detailed, varied, and multisource documentation; (2) reviewing the documentation
and identifying significant features of each crime individually across the series; (3)
classifying the significant features of the crime as either MO and/or ritualistic constructs;
(4) comparing the combination of MO and ritualistic features across the crimes to determine if
a signature exists; (5) compiling a written analysis that details the conclusions derived from
the available information.
To demonstrate these principles and the process used in reaching a conclusion, the
behavior of one particular offender across two assaults (see Sanchez– Johnson below) will
be presented in some detail. Intrinsic to this kind of analyses is familiarity with various
aspects of crime scene analyses and experience either evaluating or investigating a significant
number of serial sexual crimes.
2. Modus operandi
Law enforcement has historically analyzed crimes through behaviors of the offender that are
referred to as the MO or the modus operandi. Within the context of criminal investigative
analyses, the term modus operandi is used to encapsulate all of the behaviors that are requisite to
a particular offender successfully perpetrating a crime. As such, it encompasses all behaviors
initiated by the offender to procure a victim and complete the criminal acts without being
identified or apprehended. The MO can be quite simple or very complex with the various
degrees of sophistication reflecting the experience, motivation, and intelligence of the offender.
Douglas and Munn (1992) observed that the MO is dynamic and malleable and evolves as the
offender gains both experience and confidence in his/her patterns of criminal offending.
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598588
In serial sexual crimes, the MO evolves quite rapidly over time and can present
significant changes in a period of only weeks or months. This evolution manifests itself
as a result of experience, the natural process of maturation, and the education, criminal or
otherwise, of the offender. For example, an 18-year-old rapist who failed to use a condom
and ejaculated vaginally was later convicted because of DNA evidence recovered from the
victim. He served 7 years and was released. Within a matter of months, he raped again,
only this time, he wore a condom. The same 18-year-old rapist stole two 4-ft speakers, a
collection of CDs, and a CD player from his first victim. In the offenses after his release
from prison, he stole only money and jewelry from his rape victims. Another offender
reported studying the professional literature on his crime of choice as well as popular
magazines that discuss in detail the crime scene behavior of infamous offenders. When he
was later interviewed as part of a federally funded research grant, he met the interviewer
saying, ‘‘I know who you are. When I was raping, I did a literature search on rape and I’ve
read everything you’ve ever written.’’
Forces outside the offender can also impinge on the manner in which the crime is
implemented. The unavailability of a victim, the behavioral responses of the victim, and the
interruption of an offense by another person all represent circumstances that can change
aspects of the MO. One behavioral analyst was approached by a detective asking for guidance
regarding a series of serial rapes. He indicated that the offender had raped 16 women and had
been labeled the ‘‘First Floor Rapist.’’ When the analyst asked about a 17th report that he
found in the stack of documents, the detective asserted that the 17th offense must have been
perpetrated by another offender as it had occurred on the second floor of an apartment
building. The faulty assessment of the detective failed to capture the life contingencies that
can impact on the criminal behavior of an offender. He had obviously not considered the
possibility that the offender was unable to find a victim or to locate an unlocked window on
the ground floor that particular evening and was therefore required to execute entry into a
second floor apartment to carry out his criminal intent.
However, not all features of the MO are subject to change. If a certain behavior has worked
well for an offender and has not resulted in any unwanted outcomes, it is likely to be observed
in future crimes of the same offender. As each behavior is executed over a number of
situations, the criminal becomes more familiar with a particular series of behaviors and,
therefore, more able to anticipate the outcomes of them. As with many other aspects of
human behavior, this repetitive aspect of crime behavior affords the offender a sense of
familiarity and control that allows him to focus more intently on the sexualized or aggressive
motive for the crime.
3. Ritualistic behaviors in sexual crimes
The ritualistic aspects of a sexual crime emanate from the internal psychology of a
particular offender as opposed to the situational demands of committing a crime. These
behaviors derive from the motivation for the crime and the sexual fantasy that expresses it.
They are symbolic, as opposed to functional; as such, they are highly individualized and
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598 589
reflect the aspects of the crime scene that are unnecessary to the accomplishment of the crime,
but that are pivotal in expressing the primary motivation or purpose of the criminal act itself.
Geberth (1996) has linked this fantasy-based element of a sexual crime to the unique
psychodynamics of the individual responsible for enacting these impulses through the
The ritualistic aspects of a crime can also express themselves differently over a series
of offenses either due to the refinement and more complete reflection of their underlying
intent or fantasy substrate or through the addition of unexpectedly arousing aspects of a
prior offense. This is suspected in cases of serial rape that escalates in the degree of
physical force used by the offender, the increasingly intricate use of bindings, and the
introduction of distinctive verbal exchanges over a series of assaults. While earlier
research suggests that 75% of serial rapists do not escalate in the degree of physical
violence they inflict over time, 25% do escalate, apparently finding that more severe
degrees of violence or dominance enhances their arousal (Warren et al., 1999). In other
instances, bindings that begin as a way of restraining the victim can be seen to develop
into a very intricate process both in terms of the materials used and the manner in which
the victim is restrained. For example, one serial rapist engaged in sexual bondage with all
55 of his victims in 12 states. In his first few rapes, he bound his victims using their
clothing. Over time, he began using medical tape, precut lengths of rope, which he
brought to the crimes, and eventually handcuffs. In a different series involving sexual
murders, statements demanded of the victims became an increasingly central and salient
aspect of the crime, with specific and repetitive statements by the victim being scripted by
4. Observations regarding MO and ritual
In assessing the MO and ritualistic aspects of a crime, certain additional themes or
observations emerge from the application of this type of analysis. First, it is not uncommon
for a crime scene analyst to identify more elements of the MO than of the ritual. This is not
unexpected as the MO may include time, day, and location of the crime, the weapon used, sex
and age of victim, the offender’s mode of travel, and any number of other variables. The
ritual, on the other hand, is much more narrowly focused, being composed of those acts
specifically designed to compliment the motivation for the crime and to meet the psycho-
sexual needs of the offender.
Second, all aspects of the ritual may not be present in every crime (Douglas & Munn,
1992). The time available, mood of the offender, and external circumstances, such as a
roommate coming home, may all prevent the full repertoire of desired behavior from being
enacted. Each of these factors can result in the ritualistic aspects of the crime being diluted,
modified, or interrupted, depending on the internal state of the offender and the contingencies
of a particular crime.
Third, some features of the crime may serve as part of the ritual and not be recognized as
such by the analyst. For example, the manner used by an offender to approach his victim
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598590
would most often be viewed as part of the MO. However, one serial killer who focused only
on middle-class female victims for rape and murder used guile to convince the women to
accompany him. After his capture, he reported that he obtained an inordinate sense of power
from his ability to convince middle-class and intelligent women to go with him, a total
stranger, without having to resort to physical violence.
Fourth, some elements of the crime may function as both MO and ritual. In one particular
series, a serial rapist captured numerous adult male and female couples at gunpoint in their
homes and forced the wives to tie their husband’s hands and feet with shoelaces. Such
behavior would correctly be categorized as MO as it helped to ensure success by allowing the
perpetrator to control both adults simultaneously and to use one to immobilize the other.
However, having the wife neutralize the male ‘‘protector’’ also quite likely served as a
ritualistic feature of the crime that sexually excited the perpetrator.
Fifth, there may be instances in which one or more ritualistic aspects of the crime remain
known only to the offender (Douglas & Munn, 1992). One serial killer recorded his daily
fantasies about capturing a particular type of woman for sexual assault. He remained very
focused on victim demographics such as body style, color and length of hair, and breast size.
Such features obviously played an important psychosexual role in the offender’s crimes, but
were only recognized as being part of his ritual after the discovery of his records.
Sixth, when an ‘‘impulsive’’ sexual offender (Hazelwood & Warren, 2001) is involved, the
crime may be devoid of ritualistic behaviors. Such criminals act out with little or no planning.
Fantasy plays a very small role in their crimes and the involvement of paraphilic or other
ritualistic behavior is seldom observed with this type of offender. However, as with all human
behavior, criminal or otherwise, there will be exceptions. The reader will note such an
exception in the discussion of the Sanchez– Johnson case below.
5. The signature in sexual crimes
Douglas and Munn (1992) described the signature as the ‘‘calling card’’ of an offender.
In the current context, this term is used to describe a unique combination of behaviors that
emerges across two or more offenses. It is a pattern that may include aspects of both the
MO and the ritual. Recognition of this unique signature aspect of a crime can occur when
crime analysts and/or investigators are attempting to link two or more crimes that have
occurred in either close physical or temporal proximity or at times or locations that are
Occasionally, testimony regarding the signature of a crime series is presented in the
courtroom to enhance legal arguments that the series of crimes was committed by the same
offender. For example, this type of testimony was offered by one of the authors and
involved the opinion that the same person was responsible for a series of six rapes
(California v. Kenneth Bogard, 1996). In New Jersey, the Supreme Court reviewed similar
testimony and allowed the expert to testify regarding similarities across a series of offenses,
but did not allow the expert to offer an opinion as to whether the crimes had been
committed by the same person (State of New Jersey v. Fortini, 2000). In a different context,
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598 591
testimony regarding a review of the signature aspect of two homicides was offered by the
prosecution at a hearing to determine if they would be joined for prosecution (South
Dakota v. Robert L. Anderson, 1998). Similar to the qualification of all expert witnesses,
the analyst offering this type of testimony must be qualified through education and
experience, with the final decision regarding the reliability and probative value of the
testimony being determined by the judge and eventually by the jury.
6. A case example
At 12:50 a.m. on November 12, 1997, Margarete Sanchez (pseudonym), a 29-year-old
Hispanic woman, was found dead inside one of four large concrete sewer pipes that were
lying on the ground between a footpath and a well-traveled six-lane highway. Ms. Sanchez
left her boyfriend, Fernando Gonzalez (pseudonym), and her four children in a motel room at
about 11 p.m. to walk to a convenience store a few blocks away. When she did not return, Mr.
Gonzalez sent some teenagers to look for her. They returned without having found her and he
set out along the path. As he approached the four concrete pipes, he noticed foodstuffs lying
on the path, and when he bent down to examine the materials, he saw Ms. Sanchez’s body in
one of the pipes and cried out. Tory Smith (pseudonym), who had been working on his car
under a nearby streetlight, came over and together they removed her body from the pipe. She
wore a striped T-shirt, but was braless and nude from the waist down. Smith draped his T-shirt
over the lower portion of Ms. Sanchez’s body.
A woman who lived directly across the street from the crime scene told the police that she
and a male friend were returning to her residence at about 11:30 p.m. when she saw a light-
skinned male leave the area of the concrete pipes. Another witness, who was driving on the
six-lane highway, reported that at about 11:30 p.m., he observed two people by the pipes and
they appeared to be waving their arms. He told the police that one of them was taller and the
shorter person had bushy hair (as did Ms. Sanchez). The police found a convenience store
receipt at the scene that was dated and time-stamped at 11:29 p.m. A cheese steak sandwich
was among the items on the receipt but was not found at the scene. Also missing were the
victim’s shorts, panties, and an inexpensive necklace.
About 150 ft from the body, the police found Ms. Sanchez’s shorts and panties hanging
from a bush. The panties were inside the shorts and the right rear pocket was pulled out. A
short distance from the shorts, a partially eaten cheese steak sandwich was found on a stone
wall. The necklace was never found.
Ms. Sanchez had been brutally beaten in the upper part of her face, resulting in severe
bruising. Fists were believed to be responsible for the blunt force trauma. Her nose was
broken, her hyoid bone was fractured, and death was attributed to manual strangulation from
the front. Although there was no evidence of recent ejaculation, there were spermatozoa
present in the vagina. Mr. Gonzalez advised that he last had vaginal sex with Ms. Sanchez the
night before her death and had last had anal sex with the victim 1–2 weeks before her death.
It was the medical examiner’s opinion that the presence of the spermatozoa were not
associated with her murder.
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598592
Ms. Sanchez’s anus had been torn; however, there was no ‘‘reaction’’ to the tearing,
indicating that the tears were fresh and that she had died before the healing process could
begin. These injuries were attributed to a violent penetration either with fingers or penis. Ms.
Sanchez had been bitten at least twice on her chin and again on the outer aspect of her left breast.
The crime remained unsolved until the following April when, on one evening at about 8:45
p.m., Samantha Johnson (pseudonym), a Caucasian 36-year-old off-duty police officer, was
driving her marked cruiser to her home. She was traveling southbound on an interstate
highway when she saw a small car parked in a northerly direction in the southbound
breakdown lane. She parked in front of the smaller car and both Ms. Johnson and the male
driver got out of their cars, meeting between them. She identified herself as a police officer
and the man acknowledged her status and gave her his driver’s permit. Smelling alcohol,
Officer Johnson administered a Breathalyzer test and the man tested positive for intoxication.
She put him in her car and called for another officer to take the man to jail. The officer
informed her he could not assist for at least 40 minutes. The intoxicated driver had been
cooperative and so she told the second officer that she would wait for him.
Within 30 minutes, the man began trying to convince Officer Johnson to let him go
and ‘‘everything would be okay.’’ She later testified that he had remained calm during
their conversation, but that suddenly ‘‘...he went bonkers.’’ She recalled him hitting her
with his fists before she lost consciousness. She awakened to find him attempting to
manually strangle her from the front and she pried one of his fingers back and then again
lost consciousness. She again awoke to find herself nude from the waist down and in the
passenger seat with the man driving at a high rate of speed. Her kidnapper had driven
away with her when the second officer arrived to take custody of the man. She opened
her door and hung on as the man shouted for her to ‘‘...jump bitch.’’ She said that he
pushed her as she jumped from the car while it was traveling between 65 and 75 mph.
Amazingly, she survived.
Officer Johnson had been beaten in the upper part of her face, resulting in severe bruising
around her eyes. She had a broken nose and she had been bitten on the chin as well as the
outer aspect of her left breast. Her lower garments had been removed and although her shirt
was in place, her bra had been ripped off her body. Officer Johnson also suffered severe
vaginal and anal injuries.
7. The linkage analysis
As summarized earlier, linkage analysis involves five distinct but interrelated activities:
(1) Gathering the necessary documentation. In a series of rape cases, this phase of the
assessment focuses on the victim’s statement, police and medical reports, and, if
available, a commercial map depicting all significant locations (i.e., confrontation,
assault, release) associated with each of the crimes and the distances between those
locations. In homicide cases, such documentation would include police, autopsy, and
toxicology reports, crime scene and autopsy photographs, and, if all crimes occurred
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598 593
within a particular city, a commercial map depicting the abduction and murder sites if
known, the body disposal sites, and the distances between each of the various locations.
(2) Reviewing documentation and identify significant crime features. This phase of the
assessment allows the analyst to not only capture the significant aspects of each crime, but
to become intimately familiar with all offenses in the series and to be able to access
pertinent crime behaviors without having to search through volumes of data.
(3) Analyzing the crimes and identifying the MO and/or ritualistic behaviors. At this stage,
the analyst conducts a detailed study of the significant crime features and identifies those
factors that form the MO and those that comprise the ritual.
(4) Determining if a signature exists across the crimes. The analyst attempts to identify
whether a unique combination of behaviors exists across the series of crimes.
(5) Preparing the opinion. The written opinion should, at a minimum, include a listing of the
materials reviewed, whether site visitations occurred, a listing of those crime features that
comprise the MO and those that form the ritual, and, if present, set forth the unique
combination of behaviors that identify the signature.
The analyst should also be prepared to discuss any dissimilarities noted across the series of
crimes and why they do not negatively impact the opinion.
The person who attempted to murder Officer Johnson was arrested and convicted of
numerous felony offenses. He was extradited to the state in which Margarete Sanchez was
murdered and stood trial for that homicide. While the analyst was not allowed to testify that
the same person was responsible for both crimes, he was allowed to testify about the MO, the
ritual, and the similarities he had identified across both crimes.
8. The analysis in the Sanchez– Johnson cases
The prosecutor requested that the analyst provide two opinions: (1) the primary motive for
the attacks and (2) whether a signature existed across the crimes.
8.1. The motive
Anger was determined to be the primary motive underlying both crimes. The anger was
directed toward women in general and was preexistent to the crimes. This anger had been
acted out in a sexually violent manner and the taking of the necklace from Ms. Sanchez was
of secondary importance to her killer. Supporting this opinion were the following behaviors:
(1) both victims were brutally beaten and the amount of force was much greater than that
needed to subdue them for either robbery or sexual assault; (2) both women were manually
strangled and this is a much more personal method of killing than strangulation with a
ligature; (3) both women had injurious anal penetration, a form of sexual assault closely
associated with anger-motivated sexual crimes. Following his testimony, the analyst learned
that the killer told an informant that he grasped the victims by the vagina and anus to drag
them from one location to another.
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598594
8.2. The MO
The analyst testified that the following features formed the MO in the murder of Ms.
Sanchez and the attempted murder of Officer Johnson.
8.3. The ritual
The analyst testified that the following features formed the ritual in both cases. It is noted
that these features compliment the primary motivation of anger and also serve to sexually
excite the offender.
8.4. The signature
A signature was identified across the two crimes. In this case, the signature involved
features of both the MO and ritual. While each element of the killer’s MO had been
individually observed in other crimes by the analyst, this group of features combined with the
ritualistic behaviors identified in the two crimes formed a unique combination and, therefore,
a signature for this particular series. In other words, the co-occurrence of the functional
aspects of the MO and the more symbolic or ritualistic aspects of the crimes created the
signature of this offender in this series of crimes.
Margarete Sanchez (1997) Samantha Johnson (1998)
High-risk crime High-risk crime
Impulsively committed crime Impulsively committed crime
Similar age Similar age
Victim of opportunity Victim of opportunity
Alone at time of crime Alone at time of crime
Heavily traveled road Heavily traveled road
Occurred during darkness Occurred during darkness
Blunt force Blunt force
No external weapon used No external weapon used
Trauma to upper face Trauma to upper face
Nude from waist down Nude from waist down
Shorts and panties intertwined Pants and panties intertwined
Shirt left on, breasts free Shirt on, breasts free
No (fresh) seminal fluids on/in victim No seminal fluids on/in victim
Margarete Sanchez Samantha Johnson
Brutal facial beating Brutal facial beating
Manual strangulation from the front Manual strangulation from the front
Injurious anal penetration Injurious anal penetration
Bite to chin Bite to chin
Bite to outer aspect of left breast Bite to outer aspect of left breast
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598 595
8.5. Dissimilar features of the crime
As previously mentioned, it is important that the analyst be prepared to discuss any
dissimilarities in the series and why they do not negatively impact on the signature opinion.
The following features of the two crimes were found to be dissimilar.
Of the 11 features noted, 8 of them (race, height, weight, time, day, state, mode of travel,
and disposal site) can be attributed to the crimes having been impulsively committed
against victims of opportunity. As for the three remaining features (fractured hyoid bone,
murder, and theft of a personal item), they certainly pose no threat to the signature opinion.
Ms. Sanchez was manually strangled and her hyoid bone was consequently fractured.
Officer Johnson was also manually strangled and would have died (with a crushed hyoid
bone) had the second officer not arrived when he did and had Officer Johnson not
succeeded in escaping. It is also probable that this interruption deterred a theft from the
personal effects of Ms. Johnson.
8.6. Features other than MO or ritual
Almost invariably, there will be features of a sexual crime that cannot be accurately
described as either MO or ritual and/or that may not be fully understood by the analyst.
In this case, the taking of Ms. Sanchez’s shorts with panties intertwined, the taking of the
cheese steak sandwich, and the partial eating of the sandwich cannot be properly labeled
as either MO or ritual. Because the pocket of the shorts was turned inside out, it is
reasonable to assume that the killer took Ms. Sanchez’s shorts as he searched for money
or possibly drugs. In that the cheese steak sandwich had been partially eaten, it is
reasonable to assume that the killer was hungry even after the murder.
As with practically every sexual crime, there are also elements that may never be
satisfactorily explained. For example, the location of Ms. Sanchez body in the concrete pipe
is puzzling. It may be concluded that the killer placed her into the pipe, so that he could carry
Margarete Sanchez Samantha Johnson
Murdered Attempted murder
Sandwich/shorts/necklace taken Vehicle taken
Found in concrete pipe Found on highway
Fractured hyoid bone N/A
Victim walked to crime scene Victim drove to crime scene
Occurred at 11:30 p.m. Occurred at 8:45 p.m.
Occurred on Monday Occurred on Thursday – Friday
Victim was 5 ft 4 in. tall Victim was 5 ft 9 in. tall
120 lb 140 lb
Occurred in New Jersey Occurred in a different state
R.R. Hazelwood, J.I. Warren / Aggression and Violent Behavior 8 (2003) 587–598596
out his crime without being observed or to delay her discovery and if that is so, the act
becomes part of his MO. However, it may also be concluded that she crawled into the pipe in
an unsuccessful attempt to get away from her killer. If that is so, then it is not related to the
offender’s behavior at all.
The serial nature of a significant proportion of sexual crimes has motivated efforts to
determine ways of linking crimes committed by a single offender. In such cases, behavioral
analysis can be used to explore the likelihood that a series of crimes was committed by the same
person. An assessment of the MO and the ritual features of sexual crimes may result in the
identification of a unique combination of behaviors or signature. The signature is viewed as a
highly individualized and unique combination of habitual aspects of offending behavior
derived from the fantasy and motive for a series of crimes perpetrated by a single offender.
Likened to the human fingerprint in terms of its uniqueness, it is assumed that the combination
of behaviors observed in the signature of a crime series is so distinct as to inform not only the
investigation of multiple sexual crimes but also aspects of court decision-making regarding
Within the investigative context, this type of analysis could not only assist the investigative
team in organizing their information and networking with other police jurisdictions, but could
also help with crime prevention efforts by identifying the possible time and location of future
crimes potentially perpetrated by the same offender. When offered in the legal arena, it can
provide a framework for helping to inform judges and juries as to the various behavioral
components of serial sexual crimes and the uniqueness of a particular combination observed
across a series of offenses. As a form of crime scene behavioral assessment, linkage analysis
offers the experienced investigator or evaluator a framework for distilling a large amount of
crime scene information into a succinct comparative framework that can inform efforts to
potentially link offenses within the legal arena.
The authors would like to thank their colleagues, Mike Napier, Steve Mardigan, and Steve
Band for helpful suggestions regarding earlier versions of this manuscript.
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