ArticlePDF Available

Stability of Modus Operandi in Sexual Offending

  • Swedish National Police


Little is known about the stability of modus operandi (MO) in sexual offending. The authors studied a cohort of all sexual offenders released from prison into the Swedish community during the years from 1993 to 1997 (N = 1,303) and analyzed sexual reoffenders’ MO in terms of victim choice, offense nature, and severity, comparing prior offenses with those registered during an average 6-year follow-up. Stability in MO, explored with Cohen’s Kappa and Odds Ratios (ORs) as measures of agreement across registered sexual offenses, was high, specifically with respect to victim choice. Results are discussed in relation to sexual deviance and opportunity structure. The authors argue that assessment and management of sexual recidivism risk might benefit from information on offense MO. Furthermore, the results could inform police investigative strategies, such as linking multiple offenses committed by an unidentified offender.
10.1177/0093854804267094 ARTICLE
Karolinska Institutet
Little is known about the stability of modus operandi (MO) in sexual offending. The authors
studied a cohort of all sexual offenders released from prison into the Swedish community during
the years from 1993 to 1997 (N= 1,303) and analyzed sexual reoffenders’ MO in terms of victim
choice, offense nature, and severity, comparing prior offenses with those registered during an
average 6-year follow-up.Stability in MO, explored with Cohen’s Kappa and Odds Ratios (ORs)
as measures of agreement across registeredsexual offenses, was high, specifically with respect to
victim choice. Results are discussed in relation to sexual deviance andopportunity structure. The
authors argue that assessment and management of sexual recidivism risk might benefit from
information on offense MO. Furthermore, the results could inform police investigative strate-
gies, such as linking multiple offenses committed by an unidentified offender.
Keywords: modus operandi; stability; sexual offending; risk assessment; crime linkage
Sexual offenders are often regarded as a discrete offender subgroup
consisting of individuals exhibiting specific sexual offense behav-
AUTHOR NOTE: The authors gratefully acknowledge the financial support from
the Swedish Prison and Probation Services, the National Board of Forensic Medicine,
the Söderström-Königska Foundation, and the Bror Gadelius’ Memorial Foundation.
We would also like to thank three anonymous reviewers for their comments on an ear-
lier version of this article. Correspondence concerning this article should be
addressed to Gabrielle Sjöstedt, National Criminal Investigation Department, Crimi-
nal Intelligence Service, P.O. Box 122 56, S-102 26 Stockholm, Sweden. E-mail:
CRIMINAL JUSTICE AND BEHAVIOR, Vol. 31 No. 5, October 2004 609-623
DOI: 10.1177/0093854804267094
© 2004 American Association for Correctional Psychology
iors and preferences that are stable over time (e.g., Canter & Kirby,
1995; Ward, Hudson, & McCormack, 1997). Each offender’s collec-
tive pattern of crime-related behaviors is usually referred to as the
modus operandi (MO) of the offender (e.g., Kaufman, Hilliker, &
Daleiden, 1996; Warren et al., 1999). The assumption of sexual
offense exclusiveness and stability constitutes a crucial part of sexual
offender risk assessment, treatment, and commitment laws (Simon,
1997; Soothill, Francis, Sanderson, & Ackerley, 2000). This assump-
tion is also important in police investigative strategies when creating
links between different crime scenes based on the offender’s sexual
behavior (Grubin, Kelly, & Brunsdon, 2001). For instance, a number
of countries have implemented a large data-warehousing system,
known as ViC LAS (Violence Crime Linkage Analysis System; Col-
lins, Johnson, Choy, Davidson, & MacKay, 1998), into which infor-
mation on offending behaviors of both solved and unsolved cases are
entered to identify possible links between offenses with similar MOs.
However, previous studies of sexual offender specialization have
reached diverse conclusions regarding sexual offenders’ exclusive
engagement in sexual criminality as compared to other nonsexual
offenses, and also concerning the stability of specific sexual offense
MOs. Results from a meta-analysis indicated that sexual offenders
reoffend in general criminality, including property offenses, drug-
related criminality, and nonsexual violence, to a larger degree than
they commit new sexual offenses (Hanson & Bussière, 1998). These
results were supported by Soothill and colleagues (2000) with the
addition that sexual offenders who actually do recidivate in sexual
criminality tend to repeat previously exhibited offense behaviors. The
study by Soothill et al. followed over 6,000 sexual offenders convicted
in the United Kingdom in 1973 with regard to registered criminal
offenses during a 32-year period (from 1963 to 1994). The offenders
constituted four subgroups based on main offense in the sexual con-
viction: (a) indecent assault against a female, (b) indecent assault
against a male, (c) unlawful sexual intercourse with a girl younger
than 16, or (d) indecency between males. The results suggested that
60% of the total group had at least one conviction for any other offense
(excluding the 1973 index sexual offense), and 26% were reconvicted
for another sexual offense. The sexual recidivists were most likely to
be reconvicted of the same type of sexual offense as the main index
offense (i.e., category a,b,c,ordas referred above). Hanson, Scott,
and Steffy (1995) followed child molesters for 15 to 30 years and
compared their offending with that of nonsexual criminals. They con-
cluded that prior offense behavior predicted future offenses of the
same type. Furthermore, Guay and colleagues studied a group of 178
sexual aggressors and found that these offenders (comprising both
child molesters and rapists) remained stable in their victim
preferences across multiple offense occasions (Guay, Proulx, Cusson,
& Ouimet, 2001).
In contrast, other studies regarding temporal stability of sexual
offending MO indicate substantial offender heterogeneity and vari-
ability concerning victim preferences and offense type (Abel, Becker,
Cunningham-Rathner, Mittelman, & Rouleau, 1988; Grubin & Ken-
nedy, 1991; Simon, 1997, 2000). For example, Abel and colleagues
(1988) found considerable versatility in victim choice and amount of
physical contact when they interviewed 561 men who were referred
for clinical evaluation or treatment for possible paraphilia. During
these interviews, performed with a Certificate of Confidentiality, 20%
of the men reported offenses against both male and female victims,
more than 40% targeted victims in various age groups, 23% had both
intra- and extrafamilial victims, and 26% engaged in sexual offenses
both with and without physical contact. When specifically studying
the commission of various paraphilic acts, the authors concluded that
paraphiliacs with only one paraphilia are rare. Sexual versatility was
also described by Weinrott and Saylor (1991), who used computer-
ized self-reporting to study 99 sexual offenders included in a treat-
ment program. Among offenders classified as rapists (adult victim),
32% also reported having had sexual contact with a child. Conversely,
12% of offenders classified as child molesters revealed attempted
forcible sex with adult females. Among offenders knownto have only
molested victims outside the home, 34% had also committed offenses
within the family, and half of all offenders known to have perpetrated
incest offenses admitted to undetected abuse of a child outside the
home. Additionally, Studer, Clelland, Aylwin, Reddon, and Monro
(2000) explored the stability in offense type over time for intrafamilial
child molesters and found that more than half of all offenders with an
intrafamilial index offense also self-reported prior extrafamilial vic-
tims. Among offenders with an extrafamilial index offense, 13% had
Sjöstedt et al. / MODUS OPERANDI STABILITY 611
also sexually molested children within the family. A self-report study
of 91 child molesters found that 28% targeted both male and female
victims, and approximately 7% had also offended sexually against
adult victims (Elliott, Browne, & Kilcoyne, 1995). A substantial het-
erogeneity in offense-related behaviors has also been noted among
rapists who tend to use various amounts of instrumental, expressive,
or sadistic violence. Some rapists direct their attacks toward strangers,
whereas others target acquainted victims. Also, some offenders
committing rape engage in a wide range of sexual acts, whereas others
exclusively attempt vaginal intercourse (Langton & Marshall, 2001).
Most previous studies have explored sexual offenders’ criminal
behavior in general terms using broad concepts, such as sexual
offense type, or have explored the consistency of some single aspect
of offending behavior. Thus, there is a need to specifically focus on
multiple aspects of sexual offense MO in terms of victim choice,
nature, and severity of sexual offending, and to explore whether sex-
ual offenders tend to repeat prior offending behavior when commit-
ting new sexual offenses. Information about possible temporal stabil-
ity of sexual offense MO—that is, agreement between prior sexual
offense behavior and subsequent recidivism—could improve risk-
assessment procedures in directing postrelease crime-preventive
interventions for offenders who tend to repeat prior sexual offending
behavior. Knowledge about the nature and severity of potential sexual
reoffending could also be useful for decision making in clinical set-
tings. Furthermore, stability in sexual offense MO across separate
offense occasions could have implications for police work strategies,
such as linking crimes with an unknown perpetrator. This study set out
to specifically explore temporal stability of sexual offense MO in a
representative national cohort of sexual offenders convicted of a new
sexual offense during an average 6-year follow-up.
All adult (18 years) males convicted of a sexual offense defined
by chapter 6 of the Swedish Penal Code (representing both contact
and noncontact sexual offenses including rape, child molestation,
indecent exposure, etc.), sentenced to prison in Sweden, and released
during the years between 1993 and 1997 (N= 1,400), were included in
a retrospective follow-up study. This study cohort of sexual offenders
was highly representative of identified offenders convicted for contact
sexual offenses in Sweden. To make sure that all participants were
available for follow-up, we excluded individuals (n= 97) who had
been ordered out of the country on completion of the prison sentence.
Thus, the remaining study cohort consisted of 1,303 participants with
a mean age at release from prison of 40.95 years (SD = 11.99, range
18-77). The most severe sexual offense in the index conviction
involved child molestation in 46% (n= 597) and rape in 42% (n= 548)
of the cases, and the total group had an average sentence length of
11.85 months (SD = 8.10, range 0-83). Eighty-seven percent (n=
1134) were citizens of European countries, 4% (n= 55) had African
citizenship, 6% (n= 73) Asian citizenship, and 3% (n= 33) American
Retrospective follow-up started at release from prison and ended
on December 31, 2000, rendering a mean postrelease follow-up time
of 5.68 years (SD = 1.39, range 3-8). Information on registered
reconvictions concerning sexual (i.e., chapter 6 of the Swedish Penal
Code) and violent nonsexual offenses (i.e., homicide, assault, rob-
bery, threats [verbally or with weapon], and violence against an offi-
cer) was retrieved from the nationwide registers of the National Coun-
cil for Crime Prevention.
Modus operandi (MO) is a broad concept that includes various
aspects of an individual offender’s specific course of action prior to,
during, and following the crime in question. Modus operandi usually
involves the offender’s way of planning, getting access to and control-
ling the victim, and also specific measures taken to escape the crime
scene without being detected or recognized (Warren et al., 1999). Fur-
thermore, MO can refer to differences in victim, perpetrator, and
offense characteristics (Kaufman et al., 1996). For the purpose of this
study, we focused on certain aspects of sexual offense MO, including
specific victim characteristics as well as the nature and severity of the
Sjöstedt et al. / MODUS OPERANDI STABILITY 613
offense. Thus, further referrals to sexual offense MO should be under-
stood in terms of this subselection of offense characteristics.
Information on prior sexual offense MO was collected retrospec-
tively using individual subject files from the National Prison and Pro-
bation Administration, including written court reports from previ-
ously registered convictions (see also Sjöstedt & Långström, 2001).
Data on sexual reoffense MO were retrieved from written court
reports, including prosecutor’s plaint, parties account, and court find-
ings. Because the Swedish judicial system does not allow for plea-
bargaining, cases are seldom lost because of sexual assaults being
pled down to general assault. For practical reasons, individual offense
occasions are usually lumped together during court procedures in
Sweden. Several authors have reported on or highlighted the extensive
underreporting of sexual (re)offending that occurs when using only
data on arrests or convictions (e.g., Doren, 1998; Hanson & Bussière,
1998; Weinrott & Saylor, 1991). For example, Weinrott and Saylor
illustrated this issue with one incest offender who self-reported more
than 1,000 sexual encounters with his two daughters and another
offender who reported one sexually abusive contact with each of 200
victims. Both offenders had only one registered sexual offense. Thus,
in an attempt to get closer to the true prevalence of sexual recidivism,
we collected data from each individual event of sexual reoffending
instead of using the court conviction as the smallest unit of analysis.
This implied that if an offender was reconvicted once for child moles-
tation, this was not automatically regarded as one reoffense occasion.
Instead, we reviewed the written court report to register victim type,
nature, and severity for each individual event of offending. Offense
occasions were considered as individual events if they were separated
by time when the offender had stopped the abusive behavior
(providing an opportunity to refrain from committing another sexual
Interrater reliability estimates (Cohen’s Kappa) for data extracted
from files were calculated on two occasions—first, when prior sexual
offense MO was coded from subject files, and then again when data on
sexual reoffense MO was extracted from written court reports. Each
estimate was computed based on 20 randomly chosen cases, inde-
pendently scored by two raters, indicating excellent interrater reliabil-
ity (Cohen, 1960; mean κ= .90 [range .83-1.00] and .95 [range .73-
1.00], respectively).
Various features of sexual offense MO in terms of offender-victim
contact (noncontact vs. physical contact), penetration, death threat,
victim injury, and victim characteristics (male, < 15 years, family/
relative, stranger) were coded for prior and recidivistic sexual
Prior sexual offenses. Modus operandi characteristics in prior sex-
ual offenses were defined as follows: Noncontact offense implied a
sexual offense without physical contact (e.g., indecent exposure).
Physical contact comprised sexual offenses with any physical contact
between offender and victim including touching, fondling, or genital
contact. Penetration referred to oral, genital, or anal contact between
offender and victim. Death threat constituted both verbally expressed
threats and/or the use of weapons. Victim injury was assessed from
explicit information about victim bruises, bleeding, and so forth,
together with information about the offender’s use of violence in the
offense. It was not required that the victim had been medically exam-
ined to register the presence of victim injury. Victim male was regis-
tered when the offender had targeted a victim of male gender regard-
less of age. The absence of male victim consequently meant that the
offender only had offended against female victims. Victim < 15 years
included all victims younger than the age of 15, considered as children
in the Swedish judicial system. Victim family/related was defined as
biologically related victims as well as step relations; it was not
required that the offender lived in the same household as the victim.
Victim stranger included victims that the offender was unacquainted
with 24 hours before the offense took place. Information about vic-
tim-offender relationships defined as acquainted (but not family/
related) was not available during data collection concerning prior sex-
ual offending. Specific information on physical contact, penetration,
death threat, and victim injury was only available for the index offense
(the sexual offense that led to a prison sentence with release between
Sjöstedt et al. / MODUS OPERANDI STABILITY 615
1993 and 1997 and, thus, inclusion in this study), whereas the other
characteristics were registered if they had occurred in any prior
offense (including the index offense).
Sexual reoffending. Information on sexual reoffense MO was gath-
ered for each sexual offense occasion that was registered when
reviewing written court reports concerning sexual reconvictions dur-
ing the follow-up. The offense characteristic definitions were the
same as for prior sexual offenses. To summarize sexual reoffenseMOs
across multiple reoffense occasions, MO was coded in three different
ways: (a) for the first reoffense occasion, (b) the most frequent offend-
ing behavior across all reoffense occasions (present 50% of
reoffense occasions), and (c) prevalence of behavior during any of the
registered reoffense occasions (see Table 1). This implied that for
offenders with multiple reoffense occasions, different MOs could be
registered for the first as compared to the most frequent or any
reoffending behavior. However, for offenders with only one sexual
reoffense occasion, the MO during this single event was simulta-
neously registered as prevalent during the first, the most frequent, and
any reoffense occasion. Furthermore, when offenders targeted multi-
ple victims during a single offense occasion, characteristics of all vic-
tims were registered. For example, if one offender had seven offense
occasions involving a total of five stranger and four related victims
(having targeted multiple victims on two occasions), this offender
would be registered as having both a stranger and a related victim as
the most frequent victim relation. In parallel, this circumstance would
result in a coding of both any stranger and any family/related victim.
Temporal stability of sexual offense MO was analyzed using
Cohen’s Kappa as a measure of chance-corrected agreement between
MO of prior sexual offenses and sexual recidivism (Kappa-estimates >
.40 = fair, > .60 = good, > .75 = excellent agreement; Cicchetti & Spar-
row, 1981). Associations between prior and recidivistic sexual offense
MO were also expressed with odds ratios (ORs) with 95% confidence
intervals (95% CIs).
During follow-up, 6% (n= 75) of the total offender group (N=
1,303) were reconvicted for at least one sexual offense, and 13% (n=
166) were reconvicted for a violent nonsexual offense. Thus, violent
nonsexual reconvictions were generally more common as compared
to sexual reconvictions. Among these sexual and violent nonsexual
recidivists, a subgroup of offenders (n= 21) was reconvicted of both
reoffense types. The 75 sexual recidivists were reconvicted for a sex-
ual offense on 96 distinct sentence occasions during follow-up,
including, in total, 389 individual occasions of sexual offending (M=
5.19, SD = 10.53, Mdn = 1.00, range 1-62) directed against 276 differ-
ent victims (M= 3.68, SD = 7.13, Mdn = 1.00, range 1-45). A majority
of participants (n= 60) had one sentence occasion, 11 participants had
two, 2 participants had three, and 2 participants had four sexual
reconvictions. The sexual recidivists had a mean age at release from
prison of 37.19 years (SD = 11.53, range 20-72). Frequencies of dif-
Sjöstedt et al. / MODUS OPERANDI STABILITY 617
TABLE 1: Frequencies of Sexual Offense Modus Operandi (MO) Among Offend-
ers Reconvicted During Follow-Up (
= 75)
Sexual offending
Prior Reconviction
First Frequent Any
Offense MO
Noncontact offense 30 40 23 31 27 36 28 37
Physical contact 68 93a54 72 53 71 62 83
Penetration 40 57b23 31 24 32 29 39
Death threat 26 35 15 20 14 19 20 27
Victim injury 18 24 10 13 11 15 14 19
Male 11 15c12 16c13 18a18 25a
< 15 years 36 49c32 43 30 40 34 46c
Family/relative 16 21 14 19a14 19c14 19a
Stranger 34 46c31 43a33 45c34 46c
= 73.
= 70.
= 74.
ferent aspects of sexual offense MO can be seen in Table 1. The
average time to first sexual reoffense was 23.34 months (SD = 18.16,
Mdn = 21.00, range 0-75).
Stability of MO across prior sexual offenses and sexual
reconvictions is presented in Table 2. The results indicate that victim
choice or preference is an offense characteristic that is highly stable
over time with offending behavior directed against males, children,
family/relative, and stranger victims exhibiting Kappa-values > .40
(cf. Cicchetti & Sparrow, 1981). The likelihood that a sexual offender
who had a prior sexual offense involving a male victim would, if
reconvicted, again assault a male victim during the first sexual
reoffense occasion was 180 times higher compared to offenders who
had no prior registration of a male victim (i.e., only female victims).
The elevated risk of repeating a previous victim preference was 17
times higher for child victims, 27 times higher for family/related vic-
tims, and almost 9 times higher for stranger victims, compared to
offenders who did not exhibit these MOs in prior sexual offending.
Furthermore, it is interesting to note that none of the offenders with a
noncontact index offense were registered with a sexual offense
involving physical contact as their first or most frequent recidivistic
sexual behavior. Noncontact offenses, penetration, death threat, and
victim injury were moderately stable over time (see Table 2).
Stability over time for various aspects of sexual offense MO was
studied among all offenders reconvicted for a sexual offense in a rep-
resentative nationwide 5-year cohort of sexual offenders released
from prison. Our results suggest that the examined aspects of sexual
offense MO were quite stable over time, specifically regarding victim
preferences. These results corroborate earlier findings by Guay and
colleagues (2001). No major differences were observed when stability
was analyzed in relation to the first, the most frequent, or any expres-
sion of MO in sexual reoffending. Furthermore, sexual offenders sen-
TABLE 2: Stability of Modus Operandi (MO) in Sexual Offending Among Offenders Reconvicted During Follow-Up (
= 75)
Similar MO in Sexual Reoffending
First Frequent Any
Prior Sexual Offending Kappa OR (95% CI) Kappa OR (95% CI) Kappa OR (95% CI)
Noncontact offense .34 4.63 (1.62-13.18) .35 4.58 (1.67-12.54) .38 5.25 (1.91-14.47)
Physical contact .33 a.31 a.28 9.83 (1.44-67.19)
Penetration .32 7.36 (1.92-28.28) .30 5.32 (1.57-18.07) .31 4.42 (1.49-13.13)
Death threat .31 5.50 (1.63-18.56) .34 7.03 (1.93-25.60) .38 6.00 (1.98-18.20)
Victim injury .22 4.00 (1.01-15.91) .28 5.20 (1.36-19.91) .29 4.55 (1.32-15.62)
Male .79 180.00 (16.84-1923.87) .74 130.50 (13.07-1303.01) .60 60.75 (6.76-545.73)
< 15 years .59 17.16 (5.22-56.42) .54 13.20 (4.10-42.46) .64 22.40 (6.57-76.41)
Family/relative .61 27.00 (6.16-118.35) .61 27.50 (6.28-120.49) .61 27.00 (6.16-118.35)
Stranger .49 8.91 (3.04-26.11) .53 10.76 (3.63-31.96) .51 9.26 (3.19-26.87)
. Stability is expressed as agreement between prior offenses and reoffenses using Cohen’s Kappa and Odds Ratios (OR) with 95% confi-
dence intervals (95% CI).
a. No offenders with a nonphysical index offense had a physical offense as their first or most frequent sexual reoffense.
tenced to prison were more than twice as likely to be reconvicted for
violent nonsexual offenses compared to sexual offenses (13% vs. 6%,
The observed results could have both individual and contextual
explanations. Earlier studies have pointed out sexual deviance as a
quite stable individual trait (e.g., Hanson, 1998), which serves as an
important motivator in sexual offending (Hanson & Bussière, 1998).
Thus, because offenders’sexual deviancies are likely to be reflected in
the MO of sexual offending (e.g., the choice of male victims), an
offender with a pervasive sexual deviance would be more likely to
present a stable MO across offense occasions. A possible contextual
explanation is that sexual offending MO reflects an opportunity struc-
ture that is part of the offender’s everyday environment. One example
could be the presence of potential victims; if an offender frequently
moves in bar quarters and another perpetrator often passes by school
or playground areas, they are likely to encounter different types of
potential victims. However, it could be argued that offenders actively
seek out certain situations, which, in turn, influence the opportunity
structure. Also, offenders characterized by a generally antisocial life-
style and/or a more nonspecific sexual deviance might be less prefer-
ential when targeting victims and rely more on contextual opportu-
nity, which would be in accord with an “opportunistic” subgroup of
sexual offenders (cf. Hazelwood, 2001; Prentky & Knight, 1991).
Soothill and colleagues argued that sexual offenders could be both
“generalists” and “specialists” simultaneously (Soothill et al., 2000).
Thus, individual offenders could engage in repeated sexual offending
as part of a generally criminal lifestyle. Hypothetically, these individ-
uals may exhibit a pattern of general criminality that is more extensive
than their sexual offending, leading to the conclusion that sexual
offenders are generalists. However, when specifically studying stabil-
ity of sexual offending MO they might still exhibit a pattern that is sta-
ble and indicative of specialist behavior. This view of sexual offenders
as both generalists and specialists was supported by our results.
This study included a nationwide cohort of all sexual offenders
released from Swedish prisons during a 5-year period, a study group
highly representative for contact sexual offenders within the Swedish
judicial system. We collected information regarding each reoffense
occasion instead of relying on the judicial grouping into offense regis-
trations; this resulted in a much larger number of individual offense
occasions available for analysis.
Two possible explanations for stability in sexual offense MO have
been discussed thus far: (a) offender sexual deviance and (b) opportu-
nity structure. However, there is also the possibility that the observed
stability is an expression of procedures within the judicial system with
selection processes influencing which offenses lead to successful
identification, apprehension, and conviction of a perpetrator (e.g.,
Bachman, 1998; Guay et al., 2001). These problems are salient fea-
tures of most studies involving sexual offenders. At the same time,
sexual offenses that go unreported and offenders who never are con-
victed will seldom come to the attention of authorities, thus leaving
professionals without the possibility to intervene and prevent new
offenses by these “dark figure offenders.” Still, it is important to keep
in mind that the stability of registered sexual offense MO maynot gen-
eralize to self-reported sexual offense behavior (e.g., Abel et al. 1987;
Abel et al., 1988; Aylwin et al., 2000; Weinrott & Saylor, 1991; see
also Doren, 1998, for a thorough discussion on dark figures). Fur-
thermore, the relatively low recidivism rate yielded a limited study
group for the analyses of stability in sexual offending MO.
Our data indicate a fairly robust stability in sexual offense MO that
could inform professionals in their risk-management strategies during
conditional release or parole. Dvoskin and Heilbrun (2001) proposed
that adequate risk assessment should consider “for what, over what
period of time, under what circumstances, and in light of what inter-
ventions?” (p. 6). The results from this study support further elabora-
tion of sexual offender recidivism risk in clinical practice through
specification of potential sexual reoffense characteristics and impor-
tant risk situations. When evaluating the postrelease social context, it
could be valuable to particularly address the offender’s prior victim
preferences. Probation and parole officers, as well as other profes-
sionals working with the offender in the community, could be recom-
Sjöstedt et al. / MODUS OPERANDI STABILITY 621
mended to pay attention to changes in the offender’s social situation
that influences the criminal opportunity structure.
In addition to providing potential guidance to risk assessment and
management decisions, temporal stability in offense MO is a vital part
of investigative police work, where stability in offending behavior is a
fundamental assumption when linking multiple offenses purportedly
committed by the same unknown offender. The present results con-
cerning high stability in sexual offense characteristics could possibly
inform police practices and improve criminal investigations. Because
victim choice seemed particularly consistent across repeated offense
occasions, multiple offenses directed against the same victim type
might serve as a crude first grouping strategy in this linkage process.
Abel, G. G., Becker, J. V., Cunningham-Rathner, J., Mittelman, M., & Rouleau, J. L. (1988).
Multiple paraphilic diagnoses among sex offenders. Bulletin of the American Academy of
Psychiatry & the Law,16, 153-168.
Abel, G. G., Becker, J. V., Mittelman, M., Cunningham-Rathner, J., Rouleau, J. L., & Murphy,
W. D. (1987). Self-reported sex crimes of nonincarcerated paraphiliacs. Journal of Interper-
sonal Violence,2, 3-25.
Aylwin, A. S., Clelland, S. R., Kirkby, L., Reddon, J. R., Studer,L. H., & Johnston, J. (2000). Sex-
ual offense severity and victim gender preference: A comparison of adolescent and adult sex
offenders. International Journal of Law and Psychiatry,23, 113-124.
Bachman, R. (1998). The factors related to rape reporting behavior and arrest: New evidence
from the national crime victimization survey. Criminal Justice and Behavior,25, 8-29.
Canter, D., & Kirby, S. (1995). Prior convictions of child molesters. Science & Justice,35, 73-78.
Cicchetti, D. V., & Sparrow, S. A. (1981). Developing criteria for establishing interrater reliabil-
ity of specific items: Applications to assessment of adaptive behavior. American Journal of
Mental Deficiency,86, 127-137.
Cohen, J. (1960). A coefficient of agreement for nominal scales. Educational & Psychological
Measurement,20, 37-46.
Collins, P. I., Johnson, G. F., Choy, A., Davidson, K. T., & MacKay, R. E. (1998). Advances in
violent crime analysis and law enforcement: The Canadian Violent Crime Linkage Analysis
System. Journal of Governmental Information,25, 277-284.
Doren, D. (1998). Recidivism base rates, predictions of sex offender recidivism, and the “Sexual
Predator” Commitment Laws. Behavioral Sciences and the Law,16, 97-114.
Dvoskin, J. A., & Heilbrun, K. (2001). Editorial: Risk assessment and release decision-making:
Toward resolving the great debate. Journal of the American Academy of Psychiatry and Law,
29, 6-10.
Elliott, M., Browne, K., & Kilcoyne, J. (1995). Child sexual abuse prevention: What offenders
tell us. Child Abuse & Neglect,19, 579-594.
Grubin, D., Kelly, P., & Brunsdon, C. (2001). Linking serious sexual assault through behavior.
Home Office Research Study 215. London: Home Office.
Grubin, D. H., & Kennedy, H. G. (1991). The classification of sexual offenders. Criminal Behav-
iour and Mental Health,1, 123-129.
Guay, J-P., Proulx, J., Cusson, M., & Ouimet, M. (2001). Victim-choice polymorphia among
serious sex offenders. Archives of Sexual Behavior,30, 521-533.
Hanson, R. K. (1998). What do we know about sexoffender risk assessment? Psychology, Public
Policy, and Law,4, 50-72.
Hanson, R. K., & Bussière, M. T. (1998). Predicting relapse: A meta-analysis of sexual offender
recidivism studies. Journal of Consulting and Clinical Psychology,66, 348-362.
Hanson, R. K., Scott, H., & Steffy,R. A. (1995). A comparison of child molesters and nonsexual
criminals: Risk predictors and long-term recidivism. Journal of Research in Crime and
Delinquency,32, 325-337.
Hazelwood, R. R. (2001). Analyzing the rape and profiling the offender. In R. R. Hazelwood &
A. W. Burgess (Eds.), Practical aspects of rape investigation: A multidisciplinary approach
(3rd ed., pp. 133-164). Boca Raton, FL: CRC Press.
Kaufman, K. L., Hilliker, D. R., & Daleiden, E. L. (1996). Subgroup differences in the modus
operandi of adolescent sexual offenders. Child Maltreatment: Journal of the American Pro-
fessional Society on the Abuse of Children,1, 17-24.
Langton, C. M., & Marshall, W. L. (2001). Cognitions in rapists: Theoretical patterns by typo-
logical breakdown. Aggression and Violent Behavior,6, 499-518.
Prentky, R. A., & Knight, R. A. (1991). Identifying critical dimensions for discriminating among
rapists. Journal of Consulting and Clinical Psychology,59, 643-661.
Simon, L. M. J. (1997). Do criminal offenders specialize in crime types? Applied and Preventive
Psychology,6, 35-53.
Simon, L. M. J. (2000). An examination of the assumptions of specialization, mental disorder,
and dangerousness in sex offenders. Behavioral Sciences and the Law,18, 275-308.
Sjöstedt, G., & Långström, N. (2001). Actuarial assessment of sex offender recidivism risk: A
cross-validation of the RRASOR and the Static-99 in Sweden. Law and Human Behavior,25,
Soothill, K., Francis, B., Sanderson, B., & Ackerley, E. (2000). Sex offenders: Specialists, gener-
alists—or both? A 32-year criminological study. British Journal of Criminology,40, 56-67.
Studer, L. H., Clelland, S. R., Aylwin, A. S., Reddon, J. R., & Monro, A. (2000). Rethinking risk
assessment for incest offenders. International Journal of Law and Psychiatry,23, 15-22.
Ward, T., Hudson, S. M., & McCormack, J. (1997). The assessment of rapists. Behaviour
Change,14, 39-54.
Warren, J., Reboussin,R., Hazelwood, R. R., Gibbs, N. A., Trumbetta, S. L., & Cummings, A.
(1999). Crime scene analysis and the escalation of violence in serial rape. Forensic Science
International,100, 37-56.
Weinrott,M. R., & Saylor, M. (1991). Self-report of crimes committed by sex offenders. Journal
of Interpersonal Violence,6, 286-300.
Sjöstedt et al. / MODUS OPERANDI STABILITY 623
... Davies et Dale (1995) ainsi que Beauregard et Proulx (2017) mentionnent par ailleurs que les comportements paraphiliques sont souvent associés à un mode opératoire sophistiqué. Ceci implique de la préparation, un long processus de surveillance et de renseignements sur les activités routinières des victimes ciblées (Beauregard et Martineau, 2017a ;Beauregard et Proulx, 2017 ;Deu et Edelmann, 1997 ;Sjöstedt, Långström, Sturidsson et Grann, 2004). Sjöstedt et al. (2004) trouvent par ailleurs que les agresseurs sexuels ayant un comportement paraphilique ont un mode opératoire relativement stable et qui a tendance à se répéter en cas de délits sériels. ...
... Ceci implique de la préparation, un long processus de surveillance et de renseignements sur les activités routinières des victimes ciblées (Beauregard et Martineau, 2017a ;Beauregard et Proulx, 2017 ;Deu et Edelmann, 1997 ;Sjöstedt, Långström, Sturidsson et Grann, 2004). Sjöstedt et al. (2004) trouvent par ailleurs que les agresseurs sexuels ayant un comportement paraphilique ont un mode opératoire relativement stable et qui a tendance à se répéter en cas de délits sériels. Ces agresseurs ont besoin qu'un certain nombre de conditions soient réunies pour que l'agression qu'ils commettent soit un succès à leurs yeux. ...
... Les résultats de notre étude indiquent que les violeurs ayant un comportement paraphilique réalisent une meilleure préparation de leur crime que les individus n'en ayant aucune. Ce résultat suit ce qui avait été discuté dans les précédentes études (Beauregard et Martineau, 2017a ;Beauregard et Proulx, 2017 ;Deu et Edelmann, 1997 ;Sjöstedt et al., 2004). Cet aspect corrobore l'hypothèse selon laquelle les agresseurs sexuels avec un comportement paraphilique seraient ancrés dans un processus criminel organisé (Deu et Edelmann, 1997 ;Prentky et al., 1989 ;Ressler et al., 1986 ;Woodworth et al., 2013). ...
Full-text available
Cette étude s’intéresse à l’influence que peut avoir la présence de comportements paraphiliques sur le processus criminel des violeurs et sur le modus operandi qu’ils utilisent pour mener à bien leur acte. L’objectif de cette recherche est de tester plusieurs dimensions des comportements paraphiliques telles que leur présence ou non, leur nombre, ainsi que leur type. Cette recherche se base sur un échantillon de 3253 cas de viols commis en France, dont 2513 ont été commis par des individus sans comportements paraphiliques tandis que 740 concernent des agresseurs chez lesquels au moins une déviance sexuelle était présente. L’échantillon a été limité aux victimes âgées de plus de 16 ans qui ne connaissaient pas leur agresseur au moment des faits. La méthodologie utilisée suit une approche quantitative avec des analyses bivariées et multivariées. Trois différents modèles de régressions (binomiale, binomiale négative et multinomiale) ont été établis afin de tester les différents aspects entourant la notion de paraphilie. Les résultats indiquent systématiquement des différences entre le mode opératoire utilisé par les agresseurs ayant des troubles paraphiliques et les autres, quelle que soit la dimension testée. Cette étude présente des implications aussi bien théoriques que pratiques, concernant la compréhension du processus de décisions des agresseurs sexuels, de profilage criminel et de l’investigation policière.
... These may include "extrafamilial" and "incestuous relationships" (e.g. Abel et al., 1988;Doren, 1998;Guay et al., 2001); "within" and "outside the family" where "outside" includes victims known and unknown to the offender (Cann et al., 2007); and "family/related" and "stranger" (Sjöstedt et al., 2004) although social acquaintances were not included in either of the categories. Guay et al. (2001) differentiated relationships as "incest", "familiar" and "unfamiliar" in which neighbors were included in the "unfamiliar" category. ...
... Abel & Osborn, 1992), or may include broader caregiver relationships such as step or foster relationships (e.g. Guay et al., 2001;Sim & Proeve, 2010;Sjöstedt et al., 2004), or "someone related to the victim" (e.g. English et al., 2003). ...
... The first four categories (Related, Parental, Formal, and Social) were then reduced into one category "Known". The "Stranger" category was defined as victims who were known to the offender less than 24 hours of contacting or meeting them, similar to that used by Sjöstedt et al. (2004). Where it was unclear from the data records how the offender knew the victim, but indicated that the offender was unknown to the victim at the time of the offending, this was included in the "Stranger" category. ...
Full-text available
Aim/Background: Strict enforcement of residential restrictions has been the norm although there is a paucity of empirical evidence as to whether recidivist child sex offenders will reoffend against an unknown child having had no previous history of offending against children unknown to them. This research investigated Known to Stranger crossover of 110 men who sexually reoffended against children after release from prison. Methods: The offenders were released from prison between 1996 and 2003, and followed up until 2009 (M = 117.85 months, SD = 26.99). The mean age of the participants when first arrested for a sexual offence was 27.82 years (SD = 9.35: Range 14-68 years). Results and Conclusions: The incidence and factors associated with the risk of crossover from Known to Stranger child victims were examined, with results showing that sexual reoffending was low at 6.8%. Crossover from Known to Stranger victims was lower still; at less than 1% of the men released into the community. Despite the low base rate of the Known to Stranger group, analysis showed that offenders whose first victim was from the Social relationship domain (i.e. the offender met the victim through someone known to the offender as a work colleague, friend, or even a family member) were more likely to reoffend against a stranger child than offenders from the other Known relationship domains. Being younger in age at the time of the first sexual offense was also associated with a risk of relationship crossover. The recidivist group was most likely to be rated as medium-high to high risk of re-offending at the time of their release from prison.
... The wide variation in prevalence may be partially due to the victim choice domain under investigation. Both victim gender (i.e., male and female) and victim-offender relationship (i.e., stranger, acquaintance, intrafamilial) remain highly stable, with rates of polymorphism generally below 10% and 20%, respectively (e.g., Cann et al., 2007;Guay et al., 2001;Heil et al., 2003;Kleban et al., 2012;Sjostedt, Langstrom, Sturidsson, & Grann, 2004;Stephens et al., 2016). This is in contrast to victim age, where offenders have demonstrated the highest levels of polymorphism (e.g., offending against adults and children; Guay et al., 2001;Heil et al., 2003;Kleban et al., 2012;Stephens et al., 2016). ...
... Overall, the components associated with polymorphism highlighted the role of opportunity in the sexual offending of polymorphic offenders and supported hypotheses proposed in the literature to account for polymorphism (e.g., Guay et al., 2001). These findings suggested that regardless of the role of opportunity, victim availability and deviant sexual fantasies play a role in the sexual offending of polymorphic offenders, albeit to a different degree (Sjostedt et al., 2004). These findings reinforce the view that polymorphic offenders represent a particularly dangerous subgroup of sexual offenders, perhaps due to the opportunistic nature of their offending, which in turn leads to greater diversity in their offending behavior (Lussier, Leclerc, Cale, et al., 2007). ...
Purpose: Victim age polymorphism (also referred to as victim age crossover) describes sexual offenders who offend against multiple age groups. The present study examined whether polymorphic offenders could be differentiated from age-specific offenders based on the role of opportunity in the commission of their offenses. Methods: The current study examined age polymorphism in 72 sexual offenders who committed 361 stranger offenses. Incarcerated offenders were interviewed about their sexual offending history and provided information on their crime scene behaviors (i.e., pre-crime activities, victim selection, and behaviors during the commission of the offense, such as sexual behaviors), which was cross-checked with file information. A PCA and logistic regression were conducted using crime scene behaviors to determine latent constructs that differentiated age-specific and age polymorphic offenders. Individual crime scene behaviors were also analyzed. Results: Polymorphism occurred in 36% of offenders' sexual offense histories with most polymorphic offenders victimizing those aged 11 to 14 and at least one other age group. Compared to age-specific offenders, polymorphic offenders were more opportunistic and less concerned with the specific characteristics of their victim. Conclusion: Polymorphic offenders can be distinguished from age-specific offenders by their pre-crime decisions and the sexual behaviors committed during the offense.
... To date, empirical studies in the field of behavioral consistency have been conducted on a limited set of criminal behaviors and often on the most extreme forms of crime. Indeed, the focus of most studies has been on violent crimes, such as sexual offences (e.g., Sjöstedt et al. 2004;Woodhams, Grant, and Price 2007;Woodhams, Hollin, and Bull 2008), sexual assault (e.g., Davies 1992;Deslauriers-Varin 2013, 2014a, 2014bGrubin, Kelly, and Brunsdon 2001;Harbers et al. 2012;Lundrigan, Czarnomski, and Wilson 2010), rape (Davies, Wittebrood, and Jackson 1997;Santtila, Junkkila, and Sandnabba 2005;Labuschagne 2012a, 2012b), homicide (e.g., Bateman and Salfati 2007;Melnyk et al. 2011;Salfati and Bateman 2005;Santtila et al. 2008;Sorochinski and Salfati 2010), as well as sexual homicide (e.g., Schlesinger et al. 2010). The growing popularity of crime linkage, however, has led some researchers to explore the utility of crime linkage with a wider range of crime types, such as burglary (e.g., Bennell and Canter 2002;Bennell and Jones 2005;Bernasco 2008;Markson et al. 2010;Melnyk et al. 2011;Tonkin, Santtila, and Bull 2012;Toye 2007), car theft (e.g., Tonkin et al. 2008), and arson (Ellingwood et al. 2013;Santtila, Fritzon, and Tamelander 2004). ...
This handbook is currently in development, with individual articles publishing online in advance of print publication. At this time, we cannot add information about unpublished articles in this handbook, however the table of contents will continue to grow as additional articles pass through the review process and are added to the site. Please note that the online publication date for this handbook is the date that the first article in the title was published online. For more information, please read the site FAQs.
... The basic idea behind CP is that the characteristics of an unknown offender can be inferred from their behavior during the crime and rests upon two main assumptions: behavioral homology (offenders committing similar crimes possess similar characteristics) and behavioral consistency (offenders behave consistently across their offenses) (Turvey, 2012b). The few available studies examining these assumptions provide no or only partial empirical support (Bateman & Salfati, 2007;Bennell & Canter, 2002;Bennell & Jones, 2005;Sjöstedt et al., 2004;Woodhams & Toye, 2007). Moreover, the assumptions have been criticized for neglecting that criminal behavior is influenced by numerous different and particularly situational factors Turvey, 2012a). ...
Full-text available
The disparity between the ongoing use of criminal profiling and the lack of empirical evidence for its validity is referred to as criminal profiling illusion. Associated risks for society range from misled police investigations, hindered apprehensions of the actual offender(s), and wrongful convictions to mistrust in the police. Research on potential explanations is in its infancy but assumes that people receive and adopt incorrect messages favoring the accuracy and utility of criminal profiling. One suggested mechanism through which individuals may acquire such incorrect messages is the consumption of fictional crime-related media which typically present criminal profiling as highly accurate, operationally useful, and leading to the apprehension of the offender(s). By having some relation to reality but presenting a distorted picture of criminal profiling, fictional crime-related media may blur the line between fiction and reality thereby increasing the risk for the audience to mistake fiction for fact. Adopting a cultivation approach adequate to examine media effects on one’s perception, the present study is the first to investigate whether the perception of criminal profiling may be influenced by the consumption of fictional crime-related media based on a correlation study. Although the results provide support for the assumption that misperceptions of criminal profiling are widely spread in the general population and associated with the consumption of fictional crime-related media, the found cultivation effects are small and must be interpreted cautiously. Considering that even small effects may have the potential to influence real-life decision-making, they may still be relevant and affect society at large.
... Similarly, it has been argued that men who exhibit age polymorphism may have less specific paraphilic interests and are more opportunistic in their offending (Sjöstedt et al., 2004). Men who exhibit age polymorphism have been found to be less likely to select victims based on victim characteristics and more likely to select victims based on their vulnerability, compared with those who are stable in victim age selection . ...
Full-text available
Aim/Background Victim age polymorphism occurs when someone offends against victims that span multiple age groups (e.g., child and adult victims). There is a need to better understand the correlates of age polymorphism, as clinicians are often asked about risk of offending against victims who may differ from the index offence victim as part of their risk formulation. The present study examines several potential correlates of age polymorphism: psychopathy, sexual preoccupation, multiple paraphilias, psychosis, and substance use disorders. Materials/Method Analyses were conducted using secondary clinical assessment data from a provincial forensic sexual behaviour program. The sample included 387 men with two or more contact sexual offence victims. The assessment data in the archival database included comprehensive information about victim age, as well as standardized assessment measures and diagnostic/clinical impressions. Results There were no significant associations between age polymorphism and psychopathy, multiple paraphilias, sexual preoccupation, psychosis, and substance use disorders. The only significant difference that emerged was that men who offended against victims 16 or older had a higher mean score on a measure of drug misuse than those who offended against victims 6 to 11. Most of the analyses produced small effects. Conclusion Our findings did not identify significant correlates of age polymorphism when restricting analyses to those men who offended against two or more victims. We consider key methodological differences that may have impacted our findings, as well as the need for rigorously designed research to develop a comprehensive model of age polymorphism.
... Although intrafamilial ISOCs tend to exhibit less sexual interest in children than extrafamilial ISOCs (Firestone et al., 2000;Schmidt et al., 2014), it has been noted that there is a "lack of knowledge on the preferences of 'mixed' offenders" (Michaud & Proulx, 2009, p. 330). However, it has been argued that individuals who are less preferential in who they victimize harbor a more nonspecific/general sexual deviance (Beauregard, Leclerc, & Lussier, 2012;Sjostedt, Langstrom, Sturidsson, & Grann, 2004). In support, mixed offenders have been found to have less pre-treatment sexual deviance than child victim-only offenders (Olver, Wong, Nicholaichuk, & Gordon, 2007) and a similar phallometric response pattern towards stimuli showing consensual adult sex, rape against adult females, and non-violent sexual activity with a child (Michaud & Proulx, 2009). ...
The present study investigated whether a latency-based Go/No-Go Association Task (GNAT) could be used as an indirect measure of sexual interest in children. A sample of 29 individuals with a history of exclusive extrafamilial offenses against a child and 15 individuals with either a history of exclusive intrafamilial or mixed offenses (i.e., against both adults and children) were recruited from a treatment center in the United States. Also, a sample of 26 nonoffenders was recruited from a university in the United Kingdom. All participants completed the Sexual Fantasy-GNAT, a Control-GNAT, and two self-report measures of sexual fantasy. It was hypothesized that, relative to the two comparison groups, the extrafamilial group would respond faster on the block that paired “sexual fantasy” and “children.” Also, GNAT scores were expected to correlate with child-related sexual fantasies. Support was found for both hypotheses. Response-latency indices were also found to effectively distinguish the extrafamilial group, as well as those who self-reported using child-related sexual fantasies. The implications of these findings, along with the study’s limitations and suggestions for future research, are discussed. Keywords
Full-text available
Child sexual abuse is typically studied using reports from the offender and in Western countries. The aim of the present study was to investigate pre- and post-abuse strategies of persons convicted of a sexual offense to children in Turkey using the statements made by the child victims and to frame the results using rational choice theory. A qualitative study was made for the themes in the police statements from 46 children who were victims of child sexual abuse. The content analysis revealed that persons convicted of a sexual offense to children differ in terms of their methods to approach children and in their pre- and post-abuse behaviors depending on their relationship with the victim. A total of 85 percent of the offenses were extra-familial and 15 percent within the family. Only 21 percent of the extra-familial offenses were opportunist; most involved bribes and introductions through friends or intermediaries. Two tactics unique to Turkey were promises of marriage and the use of children as intermediaries. The use of force and blackmail was more common in the intra-familial offenses. The results of the qualitative analysis were, on the whole, consistent with results from persons convicted of a sexual offense to children’s statements, but some of the tactics used by offenders in Turkey were unique to Turkish culture.
Existing inquiries purporting to study and describe offender behaviour in stranger child abduction (SCA) have utilised an overly narrow definition of modus operandi (MO), focusing only on very outset of the offence. The study aims to reflect changes that occur as the offence proceeds and to examine whether differentiating between attempted and completed cases can provide greater understanding of MO in SCA. The MO utilised by offenders in 78 cases of SCA retrieved from publicly available U.K. sources were examined. Descriptive analysis was used to determine which types of behaviour were present. Multidimensional scaling was used to categorise these behaviours and to establish whether any relationships existed between them, with view to ascertaining whether there were any clear patterns among strategies. Results found support for differentiating attempted and completed offences, with the analysis highlighting that offenders who utilised multiple means of control, who were more aggressive, and who shifted their MO from one theme to another, were more likely to complete the offence. The study concludes that more nuanced categorisations of SCA offending approaches, which reflect change over time, are required, and argues for additional, contextual information to be incorporated into future work.
Full-text available
The present study compared the long-term recidivism of 191 child molesters and 137 nonsexual criminals. Overall, 83.2% of the nonsexual criminals and 61.8% of the child molesters were reconvicted during the 15- to 30-year follow-up period. The two groups tended to be reconvicted for distinct types of offenses. Almost all sexual offense recidivism was in the child molester group (35% vs. 1.5% in the nonsexual criminal group). The nonsexual criminals, in contrast, were responsible for almost all the nonsexual violent recidivism. In general, prior offenses of a specific type predicted future offenses of the same type. Overall, the results support the utility of developing specialized approaches for understanding and managing child molesters.
Predictions of future sexual offending have been mandated by various “Sexual Predator” commitment laws, despite historical arguments that clinicians are frequently inaccurate and over-predict violence. The basis for those arguments has been the perspective that sexual recidivism is a relatively rare event. Research is reviewed, however, with the finding that sexual recidivism for certain offenders is a rather common occurrence when the definition of recidivism is in keeping with the sex offender commitment laws. This finding is used to demonstrate that under-, rather than over-prediction of the designated violence is necessarily today's practice. Practical and ethical implications are discussed. © 1998 John Wiley & Sons, Ltd.
The assessment of sexual aggression presents many difficulties for clinicians. The tendency of offenders to minimise or deny their offending, and their frequent distrust of mental health professionals, require high levels of skill to circumvent. In addition, the multifactorial nature of rape means that assessment needs to cover a broad range of content areas and utilise a number of different methods. In this paper we suggest that a comprehensive assessment should inquire into the developmental history of rapists, social competency, attitudes and beliefs about women and sexual crimes, sexual knowledge, sexual preferences and disorders, empathy, offence variables, psychiatric history, and substance abuse. The clinical interview remains the primary method of information acquisition, and needs to be tailored to match the particular interpersonal style of rapists. The use of psychometric and physiological measures are also valuable sources of clinical data.
Using recently released data from the redesigned National Crime Victimization Survey from 1992 to 1994, this article examines those factors related to the probability of a rape victimization being reported to police and the subsequent probability of an arrest being made. The contextual characteristics examined were the victim-offender relationship, injuries sustained by victims, weapon use by offenders, marital status and age of victim, and location of occurrence. Analyses focused exclusively on one-on-one incidents of rape against adult women perpetrated by males. The only factors that appeared to significantly increase the likelihood of a rape victimization being reported to police was if the victim sustained physical injuries in addition to the rape and if the offender used a weapon. None of the contextual factors were significant in predicting the probability of police making an arrest. Implications for policy and the effectiveness of rape law reforms are discussed.
Using a computer-administered interview, self-reports of past criminal behavior were obtained from 99 institutionalized sex offenders. The sample contained both rapists and child molesters who had been mandated to receive specialized treatment. Offenders disclosed an enormous amount of undetected sexual aggression, a finding consistent with other self-report studies. Also striking was the high rate and variety of nonsex offenses. According to interview responses, nearly 20,000 nonsex crimes were committed during the year prior to institutionalization, with rapists contributing a disproportionate share. Still, child molesters, including those whose only known crime was incest, were very active in assault and property crime. The potential for utilizing sex offender self-reports in empirical research is discussed. Preliminary evidence of validity is presented.
Sexual offending is on the political agenda but there has been little research focus on the four offence categories-indecent assault against a female, indecent assault against a male, indecency between males and unlawful sexual intercourse with a girl under 16-which together comprise the vast majority of convictions for sexual offences in England and Wales. We consider the criminal record (1963-94 inclusive) of the 6,097 males convicted of one of these offences in 1973. The results are discussed in terms of criminality, heterogeneity, dangerousness and specialization. By recognizing two levels of analysis-general crime level and sex crime level-we argue that sex offenders can be both generalists and specialists; they may range widely across a spectrum of offences but still specialize within sexual offending.
The current investigation examined the predictability of adolescent sexual offenders' modus operandi based upon differences in victim, perpetrator, and offense characteristics. Questionnaires regarding modus operandi and history of victimization were completed by 179 male adolescent sexual offenders. Subgroups of perpetrators were delineated based upon their history of sexual abuse, as well as the gender, age, and relatedness of offenders' child victims. Results indicated that a history of sexual abuse was related to the selection of male victims and younger victims. Furthermore, subgroups of offenders differed significantly in the strategies they employed to build victims' trust, gain compliance with illicit sexual activity, and maintain victims' silence following the onset of sexual abuse. Implications are discussed for child sexual abuse theory and prevention, as well as for victim and offender treatment.