Commuters and Marauders: Examination of Spatial Behaviour

Journal of Investigative Psychology and Offender Profiling J. Investig. Psych. Offender Profil. 1: 121–137 (2004) Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jip.012

Commuters and Marauders: An Examination of the Spatial Behaviour of Serial Criminals REBECCA MEANEY Department of Psychology, University of New England, Armidale, Australia

Abstract The demographic characteristics of serial offenders that distinguish between the commuter and the marauder offence styles were examined. Proposed by Canter and Larkin (1993) these two styles represent competing models of criminal spatial behaviour under which the home base plays a role in offence site selection. Data on serial burglars, arsonists and sex offenders were extracted from the criminal records maintained by the NSW Police Service. The offence style of each offender’s crime series was identified in order to relate the offence style to the demographic variables, and to examine the offender’s first and last offences in a series. A commuter offence style was more likely to be adopted by burglars and generally by adult males. A marauding offence style was apparent in sex offenders and metropolitan based offenders. There was a progression in the distance travelled to offend across all crime types, as the last offence was located further from the home base by comparison with the first. These findings serve to validate the conceptual distinction between commuter and marauder offence styles. Several implications for further research are addressed. Copyright © 2004 John Wiley & Sons, Ltd. Key words: serial crime; spatial behaviour; offence style

INTRODUCTION Canter and Larkin (1993) have drawn a fundamental distinction between two types of serial criminal offender in terms of the offender’s spatial behaviour during the execution of his or her series of crimes. Marauders are said to operate in an area that is proximate to the home base; commuters are deemed to commit crimes in locations perceived as being distant from the offender’s place of residence. In short, while marauders commit their offences in their own neighbourhood, commuters go beyond this habitual zone and commit their offences in more remote residential areas. The objective of this study was to validate the proposed distinction between marauders and commuters by seeking to identify demographic and other characteristics that differentiate the two types of serial offender. *Correspondence to: Rebecca Meaney, Department of Psychology, University of New England, Armidale, New South Wales, 2351, Australia. E-mail: [email protected]

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The proposed distinction between marauders and commuters arose originally from Canter and Larkin’s (1993) model of the spatial behaviour of criminals during the execution of serial offences. This model is known as the Circle Theory of Environmental Range and it depicts criminal spatial behaviour as bearing a meaningful relationship to the offender’s home base or place of residence. During both criminal and non-criminal movement from the home base, criminals gain an awareness of their environment and subsequently utilise this information in order to identify potential targets. Earlier researchers had sought to characterise this process in some detail. Downs and Stea (1973) suggest that the process by which information is derived from the environment to enable target selection is an innate and adaptive response. The individual requires cognitive structures such as the geographical location of items and strategies that enable closer proximity to these items. Such structures are generally termed cognitive maps, and they contain information including both the location and attributes of a desired object internalised as a result of either direct or vicarious interaction with the environment (Downs & Stea, 1977). The encoding of this information is thought to vary, as some individuals are motivated to attend to specific environmental cues such as those that represent potential targets in preference to non-criminally related stimuli (Brantingham & Brantingham, 1981). In response to the successful location of a target the search behaviour is reinforced, thus suggesting search behaviour will be biased toward familiar areas such as those encountered as a result of movement to and from the home base. Subsequently, it would be expected that it is possible to rationalise and predict an individual’s spatial behaviour by exploring how they interact within the structure of their environment (Brantingham & Brantingham, 1981).

CRIMINAL SPATIAL BEHAVIOUR AND DEMOGRAPHIC FACTORS The majority of serial offenders tend to commit most of their offences in an area proximate to their home base (Brantingham & Brantingham, 1981). Additionally, the criminal range of movement is regarded as being established during both criminal and noncriminal activity, thus including sites of social interaction, employment or school, and the routes that connect these destinations (Brantingham & Brantingham, 1981). As each template of spatial behaviour is established as a result of individual experience, it would be expected that individual differences among people might influence spatial behaviour (Canter & Alison, 2000). Variables such as age, sex, race and socio-economic status have been shown to significantly influence the topographical features of cognitive maps (Brantingham & Brantingham, 1981; Downs & Stea, 1973) and may thus account for observed differences in patterns of spatial behaviour. In support of this view Orleans and Schmidt (1972, cited in Brantingham & Brantingham, 1981) found that gender and age are associated with specific social and cultural expectations that had a tendency to restrict movement, thus limiting the scope of people’s cognitive maps to an area close to their home. More recently Heth, Cornell, and Flood (2002) examined the ability of male and female children and adults to self-rate their navigating ability in relation to a newly acquired cognitive map of an outdoor area. Initially, girls indicated on a 7-point scale as having a more accurate sense of direction (M = 5.9) than did boys of the same age (M = 5.0). Females at age 33 indicated a decrease in self-reported sense of direction (M = 4.7), whilst males of the same age reported an increase (M = 5.8). These results indicate that women perceive themselves as having a lower capability to Copyright © 2004 John Wiley & Sons, Ltd.

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navigate a novel environment by comparison to men, thus suggesting that women are less likely to attempt to negotiate an unfamiliar environment (Heth et al., 2002). Matthews (1995) suggests this is largely attributable to age and sex-related parental practices in Western industrialised societies. Whilst issues of safety dictate that children must play within an area proximate to the home, girls are regarded as being more suited to play within the home whilst boys are perceived as more adventurous and thus are allowed a wider activity area such as the region proximate to the home. As a result, whilst girls regard themselves as being adept in negotiating a novel environment, parental practices prevent and discourage them from practicing this skill, resulting in a perceived decrease in this ability. Subsequently, it could be hypothesised that criminals who are young, or adult females, or from specific racial backgrounds such as Caucasian may have relatively limited cognitive maps and thereby be more likely to offend within an area proximate to their home. Conversely, criminals with more experience in negotiating a wider range of environments, apparent in adult men, would be predicted to operate in an area with a wider range of criminal opportunities evident in areas located distally from the home base. In its simplest representation the physical pattern of offender movement can be conceived as a circle that encompasses the home location at the centre. The radius of the circle is representative of the distance between the offender’s home base and the furthermost offence site. The offender’s spatial behaviour across a series of offences is proposed to be interpretable in relation to their home base, as all offence sites will be relative to this location (Canter, 1994). The distance between the home base and furthermost offence is referred to as the ‘criminal range’, defined by the greatest distance an offender is willing to travel to commit an offence (Canter, 1994). The key proposition of Canter’s (Canter, 1994; Canter & Larkin, 1993) ‘Circle Theory’ is the existence of a fixed base from which the offender travels in order to offend in a defined area. Additionally, the theory proposes that criminal spatial behaviour may be most simply conceptualised as circular, as this requires that only a single parameter, the radius, need be determined. Under Canter and Larkin’s (1993) commuter model, the offender travels away from the home base in order to commit offences (see Figure 1a). This may be attributable to either the offender having to travel as a result of a paucity of target clusters close to home, or as a result of discovering a cluster of suitable targets during non-criminally related spatial behaviour (Canter & Larkin, 1993). Additionally, this remoteness from the home base

Figure 1(a).

The commuter version of Canter and Larkin’s (1993) Circle Theory.

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Figure 1(b).

The marauder version of Canter and Larkin’s (1993) Circle Theory.

enables the offender to distinguish one region for non-criminal activities and another for crimes (Brantingham & Brantingham, 1981). The rival marauder model, based on Canter and Larkin’s (1993) marauder hypothesis and the proposals of Brantingham and Brantingham (1981), predicts that the offender moves to and from their home base in multiple directions, thus highlighting the importance of proximity to the home base rather than a geographical separation between criminal and non-criminal activities (see Figure 1b). In summary, Canter and Larkin (1993) posit that the home and offence region have little physical overlap under the commuter model, but that these do overlap under the marauder model. Canter and Larkin (1993) examined the spatial behaviour of 45 male serial rapists and found that 87% of the sample displayed a marauder offence style, which suggests that the location of the home base plays an integral role in the rapist’s choice of offence site and subsequently victim selection. Canter and Larkin (1993) suggested that this may be attributable either to the rapist attempting to economise on movement during criminal activity, or to the possibility that the marauding offence style is simply a developmental stage of criminal behaviour. The crime of rape is a highly emotional act, so the offender with a marauding offence style may have a psychological need to maintain proximity to the home base, possibly to enable a feeling of security (Canter & Larkin, 1993).

CRIMINAL SPATIAL BEHAVIOUR, CRIME TYPE AND ENVIRONMENT Kocsis and Irwin (1997) conducted an empirical examination of Circle Theory with reference to the spatial behaviour of serial rapists, arsonists and burglars. Particular attention was directed at evaluating the utility of the two competing, commuter and the marauder, models of criminal spatial behaviour following Canter and Larkin (1993). Kocsis and Irwin (1997) observed that the use of a specific offence style varies with the mode of crime. Specifically, there was a dominant trend toward the marauder pattern having been adopted in the commission of serial rape and serial arson, whilst both the commuter and marauder pattern of offending were equally as likely to occur in serial burglary. Kocsis and Irwin (1997) note that both sex offending and arson are predominantly motivated by interpersonal violence, for which a wealth of opportunities exists in any given location, and thus Copyright © 2004 John Wiley & Sons, Ltd.

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the adoption of a marauder offence style may reflect the fact that sex offenders and arsonists have no necessity to travel. This evidence prompts the hypothesis that sex offenders and arsonists will display a marauder offence style. In addition to the offender’s demographic characteristics and the type of crime committed, it is anticipated that variables that potentially influence the type of information encoded as a specific spatial behaviour will influence the offence style adopted within a set of serial offences. For example, whether the environment in which the offender operates is metropolitan or rural is proposed to influence the adaptation of specific offence styles (Brantingham & Brantingham, 1981). Offenders who operate in cities have access to a large concentration of potential offence sites, resulting in having to travel only a short distance from the home base. Additionally, the increased population concentration in cities renders the offender less prone to recognition, thereby either diminishing or negating the need to travel considerable distances from the home base in order to avoid detection. Conversely, those who operate in rural towns may typically have to travel further in order to find criminal opportunities, in addition to having to travel so as to operate in an area where they are less likely to be recognised (Barker, 2000). It is anticipated that evidence of alcohol intoxication during the commission of a crime will moderate spatial behaviour by imposing limits on the offender’s spatial template. A strong relationship exists between alcohol use and involvement in crime, particularly in the case of sexual assault (Rajaratnam, Redman & Lenne, 2000). This is in part attributable to the disinhibition effect associated with alcohol, which in turn may influence the decision-making process relating to choice of offence location and convenience of access to the victim. For example, an offender that normally commutes to commit offences in order to minimise recognition may not do so whilst under the influence of alcohol as intoxication may alleviate the criminal’s anxiety with regard to being recognised near their home region. Additionally, as alcohol impairs memory function (Rajaratnam, Redman & Lenne, 2000), offenders may be limited in the degree to which they can access their spatial template of the region, thus limiting their movements to areas they are most familiar with, such as the region around the home. This evidence prompts the hypothesis that offenders under the influence of alcohol will display a marauder offence style.

TEMPORAL PATTERNS IN SPATIAL BEHAVIOUR Kocsis, Cooksey, Irwin and Allen (2002) found no variation in offence patterns with the temporal order of offences as there was no predominant adoption of a specific offence style during either earlier or later burglary offences. On the other hand, a similar study conducted by Barker (2000) observed that generally, the earliest burglaries in a series were dominantly marauder style whilst the later offences displayed a commuter pattern. The divergence between these two empirical studies may be attributable to methodological differences such as the number of offences within a series. Kocsis et al. (2002) required a minimum of two offences, which may have resulted in an insufficient quantity of data in order to reliably establish a pattern of behaviour. The temporal development of offence styles therefore looms as an interesting psychological element of Circle Theory. The present study therefore sought to scrutinise this issue. Barker (2000) suggested that across a series of five or more burglaries, there is a progression in the distance travelled to offend. The burglar initially offends close to home and subsequently increases the distance between the home base and offence sites as well Copyright © 2004 John Wiley & Sons, Ltd.

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as changing the direction travelled. This generally results in the later crimes being located further away from the home base than the first offence. Additionally, the offence sites were distributed in a circular pattern around the home base, which Barker (2000) suggested is a result of the varying routes taken from the home to the offence sites. Barker (2000) proposed that this pattern of spatial behaviour is largely attributable to changes in the offender’s mental representation of an area. The first offence is committed close to home as the offender lacks confidence and feels most secure whilst proximate to the home base. With successive offences, the offender gains both confidence and a more comprehensive mental representation of the area, allowing for competent and adaptive negotiation including an awareness of escape routes, all of which lessens the need for proximity to a secure base (Barker, 2000). This evidence prompts the hypothesis that the first crime in an offender’s series will be more likely committed in an area closer to the home base by comparison with the last crime in a series. In summary, the following hypotheses were formulated for the study. • Hypothesis 1: Offenders who are burglars will not adopt a predominant offence style whilst offenders who are adult males, or located in a rural setting will be more likely to adopt a commuter offence style than a marauder style. • Hypothesis 2: Offenders who are arsonists or sex offenders in addition to being either juvenile, female, Caucasian, located in a metropolitan area or under the influence of alcohol at the time of their offences will be more likely to adopt a marauder offence style than a commuter style. • Hypothesis 3: The first offence in a series of crimes will be more likely committed in a region proximate to the home base by comparison with later crimes, which will be committed in a region more distant to the home base.

The sample The participants were sourced from archival data held by the NSW Police Service in Sydney and were selected on the basis of having held three or more charges for break and enter (burglary) and two or more charges for either sexual offences or malicious damage by fire (arson), which reflect the categories of criminal offences used by the NSW Police. In order to be included in the analysis each offender had to meet international criteria for serial offences, namely that the offences were committed at least one day but no more than a year apart (Kocsis & Irwin, 1998). In addition, the offender had to have an identifiable home base at the time of the offences. For the purposes of geographic comparison, data from Armidale and Tamworth constituted the rural category, whilst data from Gosford was utilised as the metropolitan comparison. Exclusion of data occurred in cases where the offender had multiple places of residence over the period of offending and where the offender was known to have no involvement in target selection. There were 136 participants, (121 males and 15 females), included in the study overall, then subdivided by criminal offence as outlined below. The 83 participants who had been charged with burglary comprised 74 males and nine females who cumulatively had committed 410 burglary offences. Thus there were about five offences per series of burglaries on average (M = 4.94, SD = 2.58), with a minimum of three and a maximum of 20 offences. The burglars were reported as ranging from 11 to 52 years in age, with a mean age of 24.8 years (SD = 8.86). Eighteen burglars were recorded as having juvenile status, whilst 64 burglars were recorded as having a Caucasian Copyright © 2004 John Wiley & Sons, Ltd.

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racial background and 19 as Indigenous. Of the total burglar participant base 11 of these individuals had reported alcohol intoxication during the commission of the crimes and 40 of the burglars had committed their offences in the Gosford area and 43 in the Armidale and Tamworth area. The database of the NSW Police Service does not use the terminology ‘rape’, rather crimes of a serious sexual nature are categorised as ‘sexual offences’ therefore this terminology will be used throughout the present study. The sample of 32 serial sexual offenders consisted of 30 males and two females who had committed a combined total of 88 offences. The average number of crimes per series was approximately three (M = 2.75, SD = 0.92), with a minimum of two offences and a maximum of six. The sex offenders ranged between 12 and 67 years in age, with a mean age of 32.5, (SD = 14.60). Four of the sexual offenders were juveniles, 26 of the total sex offenders were reported as having a Caucasian racial background and six were Indigenous. Eleven offenders had been intoxicated at the time of the offences and 16 of the sex offenders had committed their sexual assaults in Armidale and the Tamworth area whilst the other 16 were in located in Gosford. With regard to the sample of 21 participants who had committed arson, 17 of these were male and four were female, with a cumulative total of 64 offences between them, resulting in an average of about three offences per series of arson (M = 3.05, SD = 1.12), with a minimum number of two offences and a maximum of six. These individuals ranged in ages from 12 to 39, the mean age being 25.19 (SD = 7.76). Two arson participants were reported as having juvenile status, four of the arson participants were recorded as having an Indigenous racial background and 17 were Caucasian. Eight of the total arson related participants reported that they had been under the influence of alcohol during the commission of the crime, 13 had engaged in arson in the Armidale or Tamworth region, eight had been in Gosford. Offences utilised for the purpose of this study had occurred in a 3year period, commencing in 2000 and concluding in 2003. Procedure The data retrieved from the database of the NSW Police Service were divided into two categories, the first being the demographic details associated with each offender, and the second relating to the geographical distribution of each offender’s crime series termed as ‘street level data’ or simply the addresses of both the offence sites and the offender’s home address. In the case of the geographic data, the following procedures were conducted. Offence style Using the procedure adopted by Kocsis and Irwin (1997) and Barker (2000) to establish whether the offence zone is proximate or distant from the home base (marauder or commuter offence style), the location of the offences and the offender’s home base were plotted on a transparency and superimposed on a map of the corresponding region. Canter and Larkin’s (1993) procedure was used in order to plot the offence zone. Under this procedure the offence sites were examined in order to establish the two crime locations that were measured by ruler as being furthest from each other, and a circle was constructed with these two points as the diameter. According to Canter and Larkin (1993) the resulting circle is an estimate of the offence zone, and this is visually examined in order to establish whether the home base lies within or outside of the offence circle. On completion of this procedure the offence pattern was identified as either marauder (within the offence circle) or commuter (outside the offence circle) for each offender. Copyright © 2004 John Wiley & Sons, Ltd.

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General offence patterns In order to assess the temporal sequence of the offence patterns in Hypothesis 3, the distances of the first and last offence from the home base for each offender were computed using a web-based mapping program—www.whereis.com.au. This program calculates distances based upon both pedestrian and vehicular access routes between two geographical points nominated by the program operator and gives the exact distance between these two points in kilometres. The values of these distances were recorded for each offender.

RESULTS Each offender’s crime series was identified as either marauder (within the offence circle) or commuter (outside the offence circle) using the procedure described in the Methods section. Descriptive statistics of the associations between the commuter and marauder categories and the independent variables are presented in Table 1. In the following analyses marauders (coded as ‘1’), were the reference category. Hypothesis 1 predicted that burglars would not adopt a predominant offence style whilst Hypothesis 2 predicted that arsonists or sex offenders would be more likely to adopt a marauder offence style when demographic variables were taken into account. The relationships between offence style (commuter v marauder) and the type of crime were initially tested using a c2 analysis. Burglars were more likely than non-burglars to adopt a commuter offence style [c2 (2, n = 136) = 43.74, p < 0.001]. Prior to demographic variables being taken into account, arsonists were more likely than non-arsonists to assume a marauder offence style [c2 (2, n = 136) = 11.14, p = 0.001], and sex offenders were more likely than non-sex offenders to adopt a marauder offence style [c2 (2, n = 136) = 22.66, p < 0.001]. To determine exactly how crime types relate to the marauder offence style or not, post-hoc c2 were conducted. Z-scores above two are regarded as being significant (Tabachnick & Fidell, 1996). The adjusted standardised residuals (Z scores) indicate that

Table 1. Descriptive statistics indicating the percentage of cases that were classified as marauder or commuter for each of the independent variables Variable Burglary Arson Sexual offences Male Female Metropolitan Rural Adult Juvenile Alcohol used Alcohol not used Caucasian Indigenous Copyright © 2004 John Wiley & Sons, Ltd.

Marauder (%) (n = 78)

Commuter (%) (n = 58)

35 90 93 55 73 67 49 59 50 73 53 58 55

65 10 7 45 27 33 51 41 50 27 47 42 45

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Commuters and marauders Table 2.

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Post-hoc c2 analysis of offence style (marauder v commuter) and type of crime Offence style

Variable Type of crime Burglary

Count Expected Z-score Count Expected Z-score Count Expected Z-score

Arson Sex offences

Table 3.

Marauder

Commuter

Total

29 47.6 -6.6 19 12.0 3.3 30 18.4 4.8

54 35.4 6.6 2 9.0 -3.3 2 13.6 -4.8

83 83.0 21 21.0 32 32.0

Key to coding of variables

Variable Offence style Type of crime Juvenile Race Alcohol intox. Crime location Gender

Coding (1) Commuter Marauder Burglary Arson Sex offences Yes No Caucasian Indigenous Yes No Rural Metropolitan Male Female

0 1 1 0 0 1 0 1 0 1 0 1 0 1 0

(2)

0 1 0a 0

a

Reference category.

burglars were found to show significantly less marauding (Z = -6.6), arsonists showed significantly more marauding (Z = 3.3) and sex offenders showed significantly more marauding than non-sex offenders (Z = 4.8). These results are presented in Table 2. A logistic regression was performed to examine how the types of crimes predict offence styles when demographic variables are included in the analysis. This was performed using SPSS with offence style (marauder v commuter) as the outcome in regard to the following predictors: gender, identification as a juvenile, location of crime (metropolitan v regional), race, alcohol intoxication at the time of any of the offences and type of crime (burglary, arson or sexual offences). The coding system used for the variables in both the correlation and logistic regression is presented in Table 3. The goodness of fit measure, Nagelkerke R-Square indicated that the model explained 50.3% of the variance in offence style, which was an acceptable result. The Omnibus model test indicated that the model with the predictors included, fitted the data significantly better than the base model with no predictors, c2 (7, n = 136) = 63.85, p < 0.001, Copyright © 2004 John Wiley & Sons, Ltd.

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Table 4. The Spearman’s correlation of relationships between the offender’s demographic and offence style variables Variable

Gender

Juvenile

Burg

Arson

Sex Offence

Offence style

Alcohol intox.

Location

Race

Gender Juvenile Burglary Arson Sex off. Offence sty. Alcohol intox Location Race

— 0.16 -0.01 0.11 -0.08 0.11 0.07 -0.10 0.16

0.16 — -0.13 0.90 0.07 0.07 -0.11 0.17 -0.04

-0.01 -0.01 — -0.54a -0.70a 0.57a 0.27a 0.02 0.05

0.11 0.09 -0.54a — -0.24a 0.29a 0.17 -0.07 -0.02

-0.08 0.29 -0.70a -0.24a — 0.41a 0.017 0.04 -0.03

-0.11 0.07 -0.57a 0.29a 0.41a — -0.17b 0.19b -0.02

0.07 -0.11 0.27a -0.17 -0.17 -0.17b — 0.08 0.02

-0.10 0.17 0.23 -0.07 0.04 0.19b 0.07 — -0.24a

0.17 -0.04 0.05 -0.02 -0.03 -0.02 0.02 -0.24a —

a

Significant at 0.01 (2-tailed) (uncorrected). Significant at 0.05 (2-tailed) (uncorrected).

b

suggesting that the set of predictors was effective in distinguishing between marauders and commuters. The Hosmer and Lemeshow value was not significant [c2 (7, n = 136) = 12.94, p = 0.7] which indicates a good model fit (Tabachnick & Fidell, 1996). The statistic for prediction success indicated that 86% of commuters and 74% of marauders were correctly predicted with an overall success rate of 79%, which is considered statistically to be a reasonably good result (Tabachnick & Fidell, 1996). The result of a correlation amongst the variables is presented in Table 4. Hypothesis 1 had also predicted that offenders who are adult males, or located in a rural setting will be more likely to adopt a commuter (coded ‘1’) offence style than a marauder style. These predictions were not independently supported, however when sex offenders were used as the reference category, a commuter offence style was more likely to be adopted if the offender is a burglar by comparison with an arsonist or sex offender (Z = 20.31, p < 0.001). The odds that a commuter would be a burglar were 0.25 times greater than if the offender was a non-burglar. Hypothesis 2 had additionally predicted that offenders who were juvenile, female, located in a metropolitan area or under the influence of alcohol at the time of their offences would be more likely to adopt a marauder offence style than a commuter style. The logistic regression was re-analysed with arsonists as the reference category. The results indicated that it was more probable that a marauder offence style would be adopted if the offender was a serial sexual offender by comparison with arsonists and burglars (Z = 30.09, p < 0.001). The odds that an offender who adopted a marauder offence style would be a sex offender were 0.04 times greater than for non-sex offenders. If the offender was located in a metropolitan region there was a significant likelihood of adopting a marauder offence style by comparison with offenders who were located rurally (Z = 9.60, p = 0.002). The odds of an offender adopting a marauder offence style if located in a metropolitan area were 0.20 times greater than an offender located in a rural area. The prediction that Caucasians, juveniles and offenders under the influence of alcohol would be more likely to adopt a marauder offence style than the commuter style was not supported. When demographic variables were taken into account, the prediction that serial arsonists would adopt a marauder offence style was not significant therefore not supported. These results are presented in further detail in Table 5. Copyright © 2004 John Wiley & Sons, Ltd.

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Table 5. Summary of logistic regression analysis for variables and their relationship with specific offence styles (marauder v commuter) Variable Crime (all) Burglary Arson Juvenile Race Alcohol use Location Gender

B

SE

Wald Sig.

-3.692 -0.497 0.624 -0.200 0.713 -1.598 -1.396

0.819 1.070 0.588 0.570 0.646 0.516 0.765

30.088 20.307 0.216 1.124 0.123 1.218 9.602 3.325

Exp(B) 0.000b 0.000b 0.642 0.289 0.726 0.270 0.002a 0.068

0.025 0.608 1.866 0.819 2.040 0.202 0.248

a

Significant at 0.02. Significant at 0.001.

b

Table 6. Mean distances (in kilometres) (and standard deviations) of first and last offences from the home base for each offence type Variable

First offence (SD)

Last offence (SD)

10.70 (22.85) 3.30 (6.08) 1.80 (3.21)

14.78 (25.77) 4.37 (6.47) 5.25 (13.82)

Burglary Arson Sex offences

Hypothesis 3 predicted that the first crime in an offender’s series will be more likely to be committed in an area that is proximate to the home base, by comparison with the last offence which is likely to be distant from the home base. The mean distances of the first and last offences for each offence type, burglary, arson and sex offences suggest that the first offence occurs in a location closer to the home base by comparison with the last offence. The mean distances for each offence are presented in Table 6. A 3 ¥ 2 mixed design ANOVA was conducted to compare the distances travelled from the home base to the first offence and from the home base to the last offence over the three crime types. There was a significant main effect for the type of crime (burglary, arson or sex offences) and the average distance travelled on the first and last offences [F(2,133) = 3.56, p = 0.03], although the effect size was between small and moderate (partial h2 = 0.05). When the results for the crime types were considered separately the Games-Howell post-hoc analysis indicated that burglars travelled a significantly longer average distance (kilometres) to offend by comparison with arsonists (M = 8.90, SE = 2.97). Similarly, when compared with sex offenders, burglars travelled significantly greater averages distances to offend (M = 9.20, SE = 2.94). Hypothesis 3 was supported as there was a significant main effect for time as there was an increase in the average distance travelled from home to the first offence site, by comparison with the last crime [F(2,133) = 9.58, p = 0.02] (presented in Table 6). The effect size for this result was moderate (partial h2 = 0.07). There was no significant interaction effect between the type of offence and the average distance travelled on the first and last crimes. The changes in the average distances over time increased consistently between the first and last offences for all crime types [F (2, 133) = 9.30, p = 0.397]. Copyright © 2004 John Wiley & Sons, Ltd.

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With regard to the predictions associated with the commuter offence style, offenders who engaged in serial burglary were more likely than arsonists and sex offenders to adopt a commuter offence style during the commission of their crimes. It had been further predicted that this tendency to displace criminal activity a greater distance from the home base would also be associated with offenders who were adult males, or located within a rural setting such as Armidale or Tamworth, but these predictions were not supported. Offenders who had committed serial sexual offences were found to be more likely to adopt a marauder offence style than burglars or arsonists. Additionally, offenders who were located in a metropolitan area had a greater tendency to display a marauder offence style over their crime series by comparison with rural offenders. It was expected that the marauder offence style would also be adopted during the commission of arson related crimes, or when the offender was either juvenile, Caucasian, under the influence of alcohol or female. These predictions did not prove to be statistically significant. The significant findings indicate that sex offenders and those in metropolitan locations such as Gosford have a strong tendency to commit offences in a geographic region within close proximity of their homes, suggesting that perceived closeness to the home base plays an important role in both offence site and victim selection in the case of sexual assaults. The prediction that an offender would commit their first crime in a series closer to the home base by comparison with the last crime was supported, as the last offence for all three crime types was committed on average a further distance from the home base than the first crime. All three types of offenders showed a significant tendency to increase in the average distance travelled from the home base in order to commit their last crime, by comparison with their first crimes. However, burglars tended to travel significantly longer distances from home to offend than did either arsonists or sex offenders. This suggests that there is a difference in the psychological processes that underlie offence site selection over a series of offences. Finding support for the first prediction, that serial burglars were more likely to adopt a commuter offence style, suggests that there is a region geographically distinct from the home base where a significant number of burglary offenders locate their targets. This may be attributable to several factors. Serial burglary is predominantly associated with social, environmental or situational factors as opposed to individual psychopathology, which is more strongly characteristic of serial arson or sexual offending (Schlesinger, 2000). This suggests that the spatial behaviour of serial burglars may be mediated by differing motivational factors. Canter and Larkin (1993) suggested that burglars characteristically do not select targets for either personal or emotional reasons; rather, they are attempting to operate within areas that will maximise yield whilst minimising potential problems associated with transporting the stolen goods. Barker (2000) offers a further characterisation of burglars. She suggests that burglars may be distinguished as either ‘professional’ or ‘opportunist’. Professional burglars have specifically targeted a location or region to burgle in order to maximise financial gain whilst minimising risk of detection. On the other hand, opportunistic burglars tend to commit their crimes on location of a suitable target. Opportunistic burglary is regarded as being strongly associated with situational triggers such as stressful or uncontrollable life events, thus the motivation to commit a burglary eventuates as a result of anger displacement. This particular type of burglary is strongly associCopyright © 2004 John Wiley & Sons, Ltd.

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ated with a very low re-occurrence rate resulting in a minimal number of crimes within a series by comparison with professional burglary (Schlesinger, 2000). Thus, it is feasible that burglaries of a more opportunistic nature had been excluded from this study as they failed to meet the minimum requirement of at least three burglaries per series, whilst the overall average in a series was five. Similarly, professional burglars tend to work without accomplices, whilst opportunist burglars tend to have at least one other individual operating with them (Schlesinger, 2000). In order to be selected for inclusion in the present study the offender was required to clearly be the determinant in target selection and not an accomplice, which again resulted in the likely exclusion of many opportunistic burglary offenders. This proposal may in part, provide one possible explanation as to why this study yielded a divergent result with regard to serial burglars compared to the findings of Kocsis and Irwin (1997) and Kocsis et al. (2002). Additionally, the sample of serial burglars in the present study was substantially larger than those used in the earlier investigations. The current study examined the spatial behaviour of 83 serial burglars by comparison to 27 cases (Kocsis & Irwin, 1997), and 58 cases (Kocsis et al., 2002). Thus it may be that a larger sample size was required in order to reliably establish a pattern of behaviour with regards to a burglary offence style as the Kocsis and Irwin (1997) and Kocsis et al. (2002) studies had indicated an equal distribution of both offence styles over a burglary series. Lack of support for the prediction that adult males would adopt a commuter offence style may be in part attributable to adult males being associated with the greatest amount of experience in criminal behaviour (Canter, 1994). The level of experience a criminal has is positively associated with the degree of confidence they possess in their criminal abilities, thus a criminal with a greater level of experience would be less likely to need to conduct their criminal activities in an area distal to the home base. Lack of support for the prediction that rural based offenders would adopt a commuter offence style may also be explainable in terms of the geography and transport networks of Armidale and Tamworth, the towns used in the ‘rural’ category for comparison with metropolitan. Both Armidale and Tamworth do not have internal rail networks; transport within the town is limited to buses, taxis and private vehicles. For obvious practical reasons, neither bus nor taxi would provide a suitable means of either transporting stolen goods or inconspicuous getaway from a crime scene. Similarly, an unfamiliar private vehicle in a rural area is highly conspicuous and likely to be noticed by the area’s residents. Therefore the least obvious and inexpensive, most convenient mode of transport in a rural area is on foot. Consequently, the offender would be more likely to centre his or her criminal activity in whichever region that was within a feasible walking distance. The finding that offenders who had committed serial sexual offences had adopted a marauder offence style was consistent with the findings of Canter and Larkin (1993) and also Kocsis and Irwin (1997) whose research suggested that serial sexual offenders limit their offence behaviour to an area proximate to their home base. This may be attributable to the strong influence of the location of the home in determining an individual’s spatial behaviour (Canter & Larkin, 1993). Alternatively, the adoption of a marauder style of behaviour may be viewed as a manifestation of the offender’s current stage in their developmental process as criminal behaviour conducted proximate to the home may be indicative of earlier offences (Canter & Larkin, 1993). Canter and Larkin (1993) had originally established the utility of the Circle Theory of Environmental Range with regard to serial sexual offenders. However, the authors had expressed a cautionary note that there was evidence that serial sexual offenders would Copyright © 2004 John Wiley & Sons, Ltd.

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adopt a commuter offence style if they were predisposed to selecting a specific type of victim (e.g. prostitutes) who were not accessible in the region close to the home base, thus requiring the offender to travel in order to locate a desirable victim. This may suggest that in the instance of serial sexual offences, individual offender psychopathology may play a determining role in the utilisation of specific offence styles (Canter & Larkin, 1993). The prediction of offenders who were located in a metropolitan area and who would adopt a marauder offence style is consistent with the findings of previous empirical studies which suggest that metropolitan locations characteristically contain a dense clustering of potential targets, thus diminishing the necessity of travel in order to locate optimal targets (Brantingham & Brantingham, 1981). This result may also be consistent with research indicating that metropolitan areas have clusters of criminals (Rhodes & Conly, 1981). Certain metropolitan areas have high levels of ‘target attractiveness’ and ‘spatial attractiveness’ or locations which provide a high concentration of targets and also are more familiar to the offender, are encoded in more detail within their cognitive maps (Rhodes & Conly, 1981). The metropolitan area of Gosford is densely populated, has a high concentration of both residential and industrial dwellings, and has a large number of public territories such as shopping centres and commercial areas. Therefore Gosford would strongly represent the characteristics of both target and spatial attractiveness (Rhodes & Conly, 1981). The lack of evidence for juveniles adopting a marauder offence style may indicate that younger individuals who engage in criminal behaviour have predominantly been raised in families where parenting practices may have been less than adequate (Matthews, 1995). Aspects of good parenting practice such as knowledge of a child’s whereabouts may have occurred irregularly or not at all, thus restrictions in the child’s movements would not have occurred resulting in few limitations in their regional cognitive maps. Subsequently, a more wide ranging cognitive map would result in less self-imposed limitations on movement, therefore social factors may have contributed strongly to the non-significant findings with regard to juveniles. The non-significant finding on the prediction that females, arsonists, Caucasians and offenders under the influence of alcohol would adopt a marauder offence style may have been partly attributable to the low participant base, or inconsistencies in police data within these four categories. As previously noted by Canter and Alison (2000), the reliability of police information varies considerably, thus not all categories of information may have been recorded consistently with regard to variables such as alcohol intoxication and ethnicity. Lack of support for the arson related prediction may additionally lie within the differing motives of serial arsonists. Neither the psychology underlying the motive to commit a crime, or the offender’s psychopathology is categorised within police data. The incidence of serial arson is regarded to be attributable to either rational motives such as economic gain or concealment of a crime, or pathological motives such as revenge, pyromania or a manifest of severe psychopathology (Mavromatis, 2000; Fritzon, 2000). These differing motives for arson would be expected to result in variations in spatial behaviour thus the adoption of a specific offence style. That there was a progression in the average distance travelled to the last offence by comparison with the first offence across all three crime types was consistent with Barker’s (2000) findings in regard to serial burglars. With regard to serial arson and serial sex offending this may further suggest that there is a similar progression of moving further from the home base to commit crimes over time. On the commission of the first crime, Copyright © 2004 John Wiley & Sons, Ltd.

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the offender approaches the event with some trepidation, thus elects to keep the home base within some degree of proximity in order to either make a quick escape, or to have a safe location in order to savour the experience depending on the motive for the crime. Therefore, it is not surprising that serial arsonists and serial sex offenders, both crimes with a higher degree of psychological investment (Canter & Larkin, 1993) were shown on average to be committed closer to the home base. The psychological processes converting criminal intention into criminal action may have been preceded by intense fantasies of the sexual assault or arson thus the target is potentially a familiar site or person, located in a region encompassed by the offender’s non-criminal movements which would include the area around the home. Otherwise, the sex offender may be attempting to create a sense of intimacy with their victims by maintaining proximity to his or her home (Canter & Heritage, 1990). The offender may have previously had an inability to form intimate relationships with women thus engaging in a sexual act in a region that has some psychological meaning to the offender may allow a perception of intimacy with the victim. As the offender accelerates in offence behaviour, they would be expected to explore new regions in order to identify potential targets. This prediction was supported in the case of serial burglars as the last offence in a series of burglaries was committed at a location that was located a greater average distance from the home base by comparison with serial arsonists and sex offenders. Barker (2000) suggests the offender may be distancing themselves both psychologically and physically from their earlier burglaries however, it could also be that the increase in distance is relative to the burglars increase in confidence with regard to their skill and simply, to operate in an area of with more profitable targets. These results suggest there is a degree of consistency in how an offender will behave spatially when committing a particular crime. This behaviour may vary in response to the motive of the crime as crimes which may be regarded as financially driven appear to be less likely to be committed proximate to the offender’s home base, whilst crimes that require a higher level of emotional investment are committed closer to the offender’s home base. This proposal suggests that the differentiation between commuters and marauders would benefit from an investigation of the psychological factors underlying the offender’s criminal behaviour. The central objective of the current study was to validate the idea that offence styles reflect meaningful psychological processes. The results of this study suggest that the offender’s psychological motive to commit a crime may additionally underlie the adoption of either a commuter or marauder offence pattern. The utility of further differentiation between commuters and marauders as a profiling tool may prove beneficial if a pattern of behaviour has been established within a number of linked offences. However, the utility of the differentiation suggested by the current study is susceptible to several criticisms, predominantly that any examination based upon offenders who have been apprehended necessarily excludes offenders who have successfully evaded detection. Additionally, it could be suggested that not all of the offender’s criminal discourse has been reflected in the crime series examined, which could certainly result in variations as to which type of offence style ultimately prevailed. Whilst every endeavour was made to ensure equal representation between the demographic groups included in the study, there was a low representation of women, juveniles and offenders under the influence of alcohol. Similarly, the number of offences in a series for both serial arsonists (M = 3.05) and sex offenders (M = 2.75) was quite low. This may have resulted in insufficient quantity of data in order to reliably establish a pattern of behaviour. Further research in this area could be conducted with a broader range of crime types in order both to increase the participant basis (to increase statistical power) and to examine Copyright © 2004 John Wiley & Sons, Ltd.

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whether other modes of crime are associated with the adoption of a predominant spatial behaviour. Nonetheless, the results of this study strongly suggest that both the commuter and marauder offence styles are associated with offenders of specific crimes and relate to determinate stages in an offender’s criminal career thus this genus of offender profiling, when used in conjunction with other investigative techniques may greatly increase the likelihood of apprehending serial offenders.

ENDNOTE Both serial rapists known to their victims, as well as stranger serial rapists, were included in the analysis.

ACKNOWLEDGEMENTS I would like to thank Associate Professor Harvey Irwin for his invaluable assistance with this manuscript and Senior Constable Greg Allen for his patient assistance with data retrieval. I would also like to extend my thanks to Doctor Don Hine and Doctor Ian Price for their help with statistical analyses and to Professor David Canter for both his guidance and encouragement in the preparation of this manuscript. Finally, sincere thanks to John and Margaret Meaney for their assistance in plotting data.

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