Resolving the Offender Profiling Equations and the Emergence of an Investigative Psychology

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1 Resolving the Offender Profiling Equations and the Emergence of an Investigative Psychology Current Directions in Psychological Science 20(1) 5-10 ª The Author(s) 2011 Reprints and permission: sagepub.com/journalspermissions.nav DOI: / David V. Canter International Research Centre for Investigative Psychology, University of Huddersfield Abstract Determining the characteristics of an unknown offender from details of a crime is at the heart of much crime fiction. Although it has roots in the inferences made by Sherlock Holmes, Sir Arthur Conan Doyle never provided empirical evidence for Holmes inferences, or models of how such inferences can be made. Yet it ought to be possible to utilize psychological theories to derive inferences about offenders. This possibility has become a significant aspect of the new domain known as investigative psychology, which among other things seeks to establish what are called profiling equations. Although these are not equations in the literal, mathematical sense, they serve to summarize the search for consistent associations between aspects of a crime and features of the criminal that will be useful to investigations. Some progress has been made in modeling the process for establishing these links, elucidating consistencies in human actions often ignored in studies of individual differences. Keywords investigative psychology, offender profiling, SSA, radex Many studies of personality and individual differences have the objective of predicting or understanding what characteristics of a person relate to their actions in different contexts. These may, for example, use psychometric procedures to predict educational achievement and effectiveness within an organization or use clinical assessments to clarify a client s problems. The person being assessed is typically directly available to the psychologist, and the task is to elucidate what they do in other, less constrained contexts. What might be regarded as the reverse of these explorations happens in criminal investigations. Quite a lot may be known about an unidentified offender s actions from details of the crime, but little may be known about his or her characteristics. If some reliable inferences can be made about these, that can assist in locating the offender and obtaining a conviction. As D. Wilson, Jackson, and Kaur-Rana (2010), among others, have made clear, the empirical, psychological nature of the investigative inference task has been hidden by accounts of what is popularly referred to as offender profiling. These imply that these inferences are the product of some special qualities on the part of the profiler. Even where these accounts claim that the inferences are derived from some scientific process, as Hicks and Sales (2006) show in some detail, all too often these processes are much more art than science. In order to clarify the nature of the psychological model that is implicit in offender profiling, I have proposed a profiling equation, abbreviated as the A! C equation (Fig. 1; Canter, 2004). In this equation, Inferences (indicated by the arrow) are derived from Actions in an offense (crime location, time, nature of the victim, etc.) about the Characteristics of the offender that will be useful to an investigation This is not an equation in any strict mathematical sense, but rather is a clear framework for revealing the challenging task of developing and resolving the inference processes required. Nonetheless, since the equation was first proposed, there has been slow but steady progress in demonstrating that, under certain conditions, the relationships can be established between Corresponding Author: David V. Canter, International Research Centre for Investigative Psychology, School of Human and Health Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom info@davidcanter.com

2 6 Canter Fig. 1. The action characteristics (A! C) equation, a model of what is involved in profiling an unknown offender. Inference must be made about the offender from information about how the crime was committed, inlcuding its location, time, and the victim details. To make such inferences, appropriate psychological theories and models must be drawn upon. offenders actions and their characteristics (e.g., Canter & Fritzon, 1998; Davies, Wittebrod, & Jackson, 1997; Santtila, Häkkänen, Alison, & Whyte, 2003). Challenges It is noteworthy how few psychological studies allow the sort of reverse engineering implied by the profiling equations. Even those that do exist may only comment on internal psychological processes of little use to actual police cases. The information being worked with is also likely to be derived from controlled conditions in laboratories or consulting rooms and not from what people actually do in their daily lives. As a consequence, studies in this investigative psychology framework do throw light on areas of human behavior that have not been well studied. Part of the reason for the dearth of research is the difficulty of obtaining information about what actually happens in crimes. This is usually held by law enforcement agencies that are reluctant to share it with academic researchers. Police databases are also notoriously inaccurate, patchy, and unreliable. It is therefore some achievement of the various methodologies used by different researchers that they overcome some of these shortcomings and have produced results that do show consistent and interesting behavioral structures within criminal activities. Unpacking the Profiling Equations The development of inferences has to work from the information that is available about a crime. This will include everything that the police may know before the offender is identified. If there are witnesses, it can include descriptions of the offender. Accounts from surviving victims of what happened may also be very useful. In addition there is often considerable information available from the crime scene itself. How the crime location has been entered, what has been taken or left and the range of other interactions with the setting itself have all proven fruitful starting points (e.g., Davies et al., 1997; Farrington & Lambert, 2000). But what has been shown to be especially productive has been the actual location of the crime scene (e.g., Levine, 2009; Sarangi & Youngs, 2006). The central psychological task is to derive inferences from all this information. This can be done on a purely empirical basis by searching databases for similar information in solved crimes and establishing the characteristics of known offenders associated with that. This runs the risk of merely giving an account of features common across many crimes that are loosely similar to each other. However, Bache and his colleagues (Bache, Crestani, Canter, & Youngs, 2010) have recently had some success with techniques that use the sort of information retrieval now commonplace in computer comparisons of the form people who bought this also bought... These take account of prior probabilities using Bayesian statistics and thus are more discriminating. The disadvantage of these purely empirical procedures is that they rely on large data sets that are rarely available. Also, they are somewhat a black box in that there is no conceptual or theoretical modeling of the central relationships. The results are generated entirely from within the data. This makes their replicability with different data sets open to question. A more conceptually driven approach is to try to establish generic models that incorporate both actions and characteristics. As Youngs (2007) has argued in some detail, it is not to be expected that there will be any simple one-to-one relationship between a given action and a specific feature of the offender. Therefore, broader frameworks that take account of the circumstances of the crime and are based on general

3 Investigative Psychology 7 Fig. 2. A developed framework for the profiling equations. This is a more detailed elaboration of Figure 1, listing the main classes of information available about the crime and the forms of psychological processes that are relevant for making inferences relevant to an investigation. The various forms of conclusion that are relevant beyond merely describing the likely characteristics of the offender are also indicated (under Outcomes ). psychological assumptions about consistencies in personality and an individual s actions are likely to prove more fruitful. These frameworks are built on the recognition that there are aspects of offenders and their experiences that psychologists would hypothesize to be a foundation for relationships between actions and characteristics. Such foundations may be found, for example, in what the criminal s actions reveal about his or her intelligence. The emotional lability exhibited in a crime could be another illustration of the offender s personality. In general, though, research as illustrated by Youngs (2004) indicates that it is the typical way of relating to other people that is the most fruitful basis for making inferences about a criminal from what he or she does in a crime. How the offender deals with a victim, or whether the offender actually seeks to avoid direct contact with the victim, is likely to be helpful in determining what sort of person the criminal appears to be in noncriminal situations. More abstract theories building on those aspects of offending that can be used to make inferences about offender characteristics have also found some empirical support most notably an action system framework (Canter & Fritzon, 1998), which draws on systems theory to argue that the source and target of a crime combine to generate a style of offending that predicts important features of a criminal. More recently this action system framework has been developed to incorporate a narrative framework. This Narrative Action System (NAS; Canter & Youngs, 2009) is built on earlier studies of offenders narratives (Canter, Kaouri, & Ioannou, 2003). The NAS recognizes the social context of crimes and the ways in which offenders play different roles in their criminal activities. M. Wilson and Smith (2000) show the importance of understanding offender narratives for making sense of terrorist activity. Donald and Wilson (2000) also show the power of the underlying plot offenders are acting out by the way in which role differentiation occurs in criminal gangs. The different parts played relate directly to criminals offending history. There are a number of outcomes of the investigative psychology process beyond trying to give some investigatory useful indications of the features of an unknown criminal. These include linking crimes to a common offender (Woodhams, Hollin, & Bull, 2007), which is based on explorations of how consistent a serial offender s actions are from one crime to the next (Salfati & Bateman, 2005). The most productive outcome has proven to be the indication of the possible location of an offender s home or base, as shown, for example, by Warren et al. (1998) and many others, reviewed in Canter & Youngs (2009). The general framework that covers the profiling equations is summarized in Figure 2. Behaviorally Based Classifications All of the processes in the inference model rely on being able to determine what is distinct about any given crime its salient features (Canter, Alison, Alison, & Wentink, 2004). A considerable amount of investigative psychology has therefore focused on determining what is common across any type of crime and what distinct subsets can be identified (e.g. Salfati & Bateman, 2005). This work challenges the claims that offenders can be neatly classified into distinct subgroups and, as Taylor, Bennell, and Snook (2002) discuss, raises important

4 8 Canter bite marks SEXUAL CONTROL gagging MUTILATION facial disfigurement parts missing weapon left in victim restraints body covered ligature strangulation improvised murder weapon multiple crime scenes dismember mutilate thoracic isolated location violence genitalia concealed posed body >50% 20-40% 10-20% <10% mutilate genitalia victim alive for sex object penetration rape bludgeoned disembowel missing weapon beaten PLUNDER tampered overkill evidence multiple sex acts belongings scattered mutilate abdomen clothing scattered decapitation trail of clothing EXECUTION manual strangulation throat cut firearm victim burned ransacking Fig. 3. Radex model of serial killers actions (Canter and Youngs, 2009). The points in the configuration are the actions. They have been placed in this notional Cartesian space on the basis of their co-occurrence. The more likely the actions are to occur in the same crime, the closer together will those actions be in this space. Straight lines have been drawn to indicate the border between the regions of similar crimes. The four resulting regions have each been given a label as they would in a factor analysis. They therefore indicate the four modes of actions of these 100 serial killers. Superimposed on this qualitative facet that has four elements is the quantitative facet that has the concentric circles of frequency. These frequencies relate to the extent of depravity of the actions. For instance, at the very extreme are dismemberment and disemboweling, whereas close to the center is concealing a weapon and sexual activity. questions about the appropriate way to distinguish between subsets of offending activity. Direct tests of proposed offender typologies, for instance for serial killers (Canter et al., 2004), show that a much more complex set of overlapping themes distinguish offenses. These overlapping themes have also been found across crimes as varied as pedophilia (Canter, Hughes, & Kirby, 1998), rape (Canter & Heritage, 1990), and arson (Canter & Fritzon, 1998). What has emerged consistently is a radex model of criminal actions, as illustrated in Figure 3 for serial killers. Although there have been some challenges to the empirical validity of this model (e.g., Sturidsson et al., 2006), Davis (2009) has clearly shown that these are based on confusions and errors in the understanding and use of the procedure. Indeed, Hammond (in press) has recently shown in a very thorough statistical analysis that the radex model is remarkably empirically robust provided the appropriate measures of co-occurrence between criminal actions are used. Cross-validation studies, notably for homicide and rape, have also provided support for the validity of the model (reviewed in Canter & Youngs, 2009) The radex model first proposed by Guttman (1954) as a general model for many psychological phenomena being, as he saw it, a new approach to factor analysis consists of two components. In the study of criminal behavior the radex is derived from analysis of the co-occurrence of actions across many crimes. One component is the division of the variations in criminal behavior into qualitative elements, each reflecting a distinct kind or mode of behavior. These are reflected, typically,

5 Investigative Psychology 9 in what has become known as a circumplex because they relate to each other in a circular manner as, for example, do colors in the color circle. The other is the quantitative ordering from least to most intense. This may be the degree of seriousness of the crime or the extent of depravity the actions exhibit. In most cases this directly reflects frequency of the actions, the most extreme being the rarest. The least intense actions will tend to occur together, and the rare actions will be more specific to particular subsets of crimes. The analysis will reveal this structure in a pattern in which there are a series of concentric contours with the most extreme behaviors on the outermost regions and ever less intense actions as the contours move toward the centre of the configuration. Thus this quantitative facet is a modification of the modes of criminality that the qualitative facet distinguishes. An example of a radex structure makes this easier to understand. A typical radex is therefore given in Figure 3. The actions on which this is based are derived from the content analysis of the third homicide carried out by each of 100 serial killers. A nonmetric multidimensional scaling procedure is used, known as smallest space analysis (SSA), which represents the co-occurrences as distances in the space, such that the higher the likelihood that any action happens in the same crime, the closer together those actions are in the resulting configuration. The configuration represents the actions as points in a notional space. The SSA procedure does not incorporate information about the frequencies of the crimes. Therefore the fact that the frequencies do map directly onto the resulting SSA space as indicated in Figure 3, rather than being randomly spread around it, is a significant empirical discovery (cf. Hammond, in press). The pattern shown in Figure 3, with the frequencies tending to form concentric regions with a quantitative order from the innermost region that has high frequencies to the outermost that has the lowest, is one that has been found with many different data sets. In the example here, it implies that there are actions that are common to all serial killings, which are at the core of the configuration. These turn out to be the sorts of actions that have been described as organized behaviors, thereby showing that there is no empirical support for this being a distinct type of killing. The differentiation between killings derives from the less frequent actions. It is those qualitative variations that provide the basis for identifying what is salient for each crime and consequently provide a solid basis for making inferences. Conclusions Although stimulated by popular accounts of offender profiling, investigative psychology has established a scientific framework for drawing inferences about offenders characteristics from criminal actions. Studies have shown that under certain conditions psychological consistencies in criminals personalities and aspects of their experiences can provide the basis for resolving profiling equations. This is not only useful to police investigations; it also points to the value of studying variations in human actions in specific situations outside of the constraints of the laboratory, clinic, and classroom. The general models of differences in criminal actions that are emerging may therefore be the forerunner of related models in other areas of human behavior. Recommended Reading Canter, D., & Youngs, D. (2009). (See References). A recent textbook providing a thorough review of the whole field of investigative psychology, from interviewing to terrorist networks. Declaration of Conflicting Interests The authors declared that they had no conflicts of interest with respect to their authorship or the publication of this article. References Bache, R., Crestani, F., Canter, D., & Youngs, D. (2010). A language modelling approach to linking criminal styles with offender characteristics. Data & Knowledge Engineering, 69, Canter, D. (2004). Offender profiling and investigative psychology. Journal of Investigative Psychology and Offender Profiling, 1, Canter, D., Alison, A.J., Alison, E., & Wentink, N. (2004). The organized/disorganized typologies of serial murder: Myth or model? Psychology, Public Policy and Law, 10, Canter, D.V., & Fritzon, K. (1998). Differentiating arsonists: A model of firesetting actions and characteristics. Legal and Criminological Psychology, 3, Canter, D.V., & Heritage, R. (1990). A multivariate model of sexual offences behaviour: Developments in offender profiling. 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