Cleaning up your act: Forensic awareness as a detection avoidance strategy
Research Highlights
► The study introduces the concept of forensic awareness as a detection avoidance strategy; ► Offenders are inconsistent in their forensic awareness; ► Forensically aware offenders are more preoccupied with protecting their identity than destroying or cleaning up DNA left at the crime scene;
Introduction
When contemplating the decision to commit a crime, most offenders have to answer two related questions: What do I need to do to successfully commit this crime? and What do I need to do to avoid getting caught? The response to these two questions lies in the offenders’ modus operandi, which refers to the pattern of actions and behaviors prior to, during, and following the illicit act in order to perpetrate the offense successfully (Hazelwood and Warren, 2004, Sutherland, 1947). This modus operandi is conceived as a dynamic process which needs to be adapted to situational circumstances (Cornish, 1993). Although criminals have shown their capacity to adapt and develop new and innovative ways to commit crimes, the criminal justice system is attempting to catch up and better react to detect and apprehend offenders. One of these strategies used especially in cases of violent crimes is the increased reliance on the analysis of forensic evidence (e.g., DNA) to apprehend offenders. Whether or not influenced by TV shows such as CSI or Law and Order, some offenders are now more aware of these forensic techniques and make sure to destroy or clean up evidence that may have been left at the crime scene to avoid detection (Stevens, 2008). Although quite a lot of research in the rational choice tradition has investigated how offenders successfully commit certain crimes, clearly there is a lack of empirical studies looking at the factors associated with the use – or not - of certain detection avoidance strategies. The current study introduces the concept of “forensic awareness” as a detection avoidance strategy, and proposes to examine the factors associated to its use in a large sample of convicted sex offenders.
In criminology, the rational choice perspective is a theoretical framework specifically designed to address offender decision-making in the course of a specific crime (Cornish and Clarke, 1986, Cornish and Clarke, 1987). The rational choice perspective assumes that criminals offend because crime provides the most effective means of achieving desired benefits (e.g., sexual gratification). As a corollary, the choice of methods for carrying out these crimes is best regarded as instrumental behaviors to achieve these goals (Cornish & Clarke, 2002). Offenders decide whether or not to commit a crime by weighing the effort, rewards, and costs involved in alternative courses of action. The making of decisions and choices, however rudimentary this process might sometimes be, exhibits a measure of rationality, albeit constrained by limits of time, ability, and the availability of relevant information (Johnson & Payne, 1986). In fact, an offender's cost-benefit analysis may not take into account every possibility, both because such an analysis is time-consuming and because the relevant information is only partially available to him. In addition, an offender's cognitive deficits may restrict his information-processing concerning the crime (e.g., an offender intoxicated prior to the crime, see Shover, 1996, Shover and Honaker, 1992). Consequently, offenders usually rely on heuristics partially based on the success and failure of previous criminal activities, including previously used detection avoidance strategies which did not lead to apprehension. The course of action selected by an offender is usually the first minimally satisfactory one identified, rather than the optimal one (Tversky & Kahneman, 1981).
The crime-commission process involves different stages. One of these stages deals with how the offender “exits” the crime scene and attempts to avoid detection (Cornish & Clarke, 2002). In order to avoid arrest, offenders have to rely on specific strategies. However, there exist potentially as many strategies as there are different types of crimes and criminals. Jacobs, 1996a, Jacobs, 1996b in expanding the concept of “restrictive deterrence” – which refers to any strategies employed by the offender to evade detection (Gibbs, 1975) - suggested two distinct types: probabilistic (reduction of offense frequencies based on a “law of averages” mentality) and particularistic (reduction in offense frequencies based on tactical skills offenders use to avoid apprehension). Jacobs (1996b) distinguishes further the particularistic deterrence into reactive and anticipatory dimensions. Reactive restrictive deterrence (RRD) concerns the strategies used by offenders to filter or neutralize social control agents (and/or their related apparatus) before offenses are committed. Anticipatory restrictive deterrence (ARD) includes specific strategies used by offenders to avoid detection regardless of direct contact with social control agents. One example of ARD that has been constantly found to be effective for different types of crime concerns target selection. In his study of crack dealers, Jacobs (1996a) identified a “perceptual shorthand” offenders use to determine whether potential buyers are narcs. This specific form of target selection focuses on three aspects pertaining to the buyer: (1) the appearance (e.g., clean versus filthy appearance, large clothes to hide wires or bulletproof vest, driving a four-door van that could be loaded with police), (2) verbal clues (e.g., soliciting crack improperly, unacceptable stylistic ways of conducting transactions), and (3) testing (e.g., forced drug use of the spot, asking who the buyer knows in the area). Similarly, in a study on active burglars, Wright, Logie, and Decker (1995) found that compared to non-burglars, active burglars possess an “expert knowledge” for selecting targets (e.g., the unimportance of an extra lock and property marking, being able to notice certain environmental changes) which increases their ability to avoid apprehension (see also Weaver & Carroll, 1985 on shoplifters).
Most of the studies examining strategies to avoid detection have been carried out on property/drug offenders. Arguably, target selection is as important in violent offense as it is for other type of offenses (see Warr, 1988). However, in violent crimes such as sexual assaults, in addition to appropriate target selection, offenders must make sure to clean up or destroy forensic evidence - the evidence that may be left at the crime scene and that can directly lead to their identification. In those cases, offenders will show more or less “forensic awareness”, a strategy which we introduce in more details below.
In the past 20 years, the use of forensic evidence in criminal investigation has increased significantly, due in part to the technological progress achieved to analyze even microscopic piece of evidence (Beaver, 2010, Strom and Hickman, 2010). To commit their crimes, offenders take actions that inherently have the potential to leave evidence on the crime scene. For instance, the use of a weapon may be traced back to the offender by analyzing the fingerprints left on a knife or through ballistic in case of a gun. The use of restraints may be linked to the offender by analyzing fibers recovered at the crime scene. A sex offender who has penetrated the victim and has ejaculated could be linked to the crime by his DNA. Despite all these potential opportunities, unavailability of many forms of forensic evidence has been observed at crime scenes (Cole, 2010). In fact, research has shown that physical evidence is being collected in less than 10 percent of cases investigated by the police (Horvath & Meesig, 1996). Although little empirical evidence has been found for the “CSI effect” – by which juries supposedly will no longer convict without forensic evidence – (Cole, 2010, Podlas, 2006, Tyler, 2006), some authors have contended that perhaps a more serious aspect of the availability of all these TV shows is the knowledge gained by potential criminals (Durnal, 2010). For example, it has been noted that offenders are increasingly wearing gloves to avoid leaving fingerprints, using tape to seal envelops to avoid leaving DNA, and even using bleach (which destroys DNA) to clean up blood (Stevens, 2008). Taking additional steps and adapting the modus operandi used in a crime to hide evidence in order to ultimately avoid apprehension is now being known as “forensic awareness” (Davies, 1992).
Research on forensic awareness during the crime-commission process is scant. A number of studies looking specifically at sexual crimes identified certain strategies related to forensic awareness. Davies and Dale (1995) examined stranger rapists and suggested that an offender travelling longer distances to commit a crime may be an indicator of forensic awareness. Moreover, in their study of sexual murderers, Beauregard and Field (2008) suggested that offenders who moved the victim's body after the murder to delay detection and therefore make apprehension difficult showed a higher degree of forensic awareness.
Nonetheless, two main hypotheses have been suggested to explain the formation of forensic awareness by offenders. First, the amount of publicity given to the importance of the evidence used to apprehend criminals – the so-called “CSI effect” - may be increasing offenders’ recognition of the need to become forensically aware. Second, forensic awareness may be an indication that the offender has had previous encounters with the criminal justice system, and may be educated in the idea of evidentiary procedure, and therefore being knowledgeable in the necessity to remove evidence from a crime scene (Davies, 1992). This latter hypothesis seems to find support in two studies in particular. In a study comparing the behaviors of single and serial rapists, it was found that offenders with a more extensive criminal career were more likely to exhibit signs of forensic awareness (Park, Schlesinger, Pinizzotto, & Davis, 2008). Similarly, Davies, Wittebrood, and Jackson (1997) in their examination of criminal antecedents of 210 cases of solved stranger sexual assaults, found that in cases of rape, offenders who destroyed semen, took fingerprint and sighting precautions were approximately 2 to about 4 times more likely to have prior convictions for sexual offenses. On the other hand, if an offender did not take precautions in leaving the crime scene, he was more likely to be a first time sexual offender and may have been under the influence of drugs at the time of the crime, thus explaining why their mental capacity to be cautious in departure precautions was diminished (Davies et al., 1997).
Although interesting, previous examinations of forensic awareness have failed to provide an adequate understanding of this particular strategy to avoid detection. The suggested hypotheses – prior contact with the criminal justice system and the CSI effect – are presented as characteristics of the offender, neglecting the situational aspect of the criminal event. For example, it could well be that offenders take forensic precautions in some crimes while being less cautious in others because of their mental state (e.g., intoxication, highly sexually aroused). While the absence of systematic research on forensic awareness exclude the formal testing of hypotheses, the present work is nonetheless guided by the following three working hypotheses: (1) offenders under the influence of disinhibitors (drugs and/or alcohol, pornography) will have their decision-making affected (e.g., make riskier decisions) and will exhibit less forensic awareness at the crime scene; (2) offenders using specific target selection strategies (expert knowledge) will also exhibit more signs of forensic awareness; and (3) offenders whose specific actions involve direct contacts with the victim and/or the crime scene may potentially leave evidence (e.g., offender breaking and entering in the victim's residence may potentially leave prints evidence) will be more likely to show forensic awareness.
Section snippets
Sample
One of the particularities of this study is that the main unit of analysis is the crime event, as opposed to the offender himself. Focusing on events is important for two reasons: 1) forensic awareness should not be assumed to be an inherent characteristic of the offender, but should be construed as being dependent on a specific context; 2) offenders do show variation in forensic awareness – experienced offenders have been shown to be more aware than novices (Park et al., 2008). Conversely, we
Results
We start by examining the prevalence of forensic awareness behaviors manifested at each crime event. As showed in Table 1, more than half of the rape events of the sample showed some signs of forensic awareness. The most common specific strategies used by offenders had to do with protecting their identity (i.e., concealing his identity, preventing his face from being seen, wearing gloves). This means that most of the DNA removal behaviors were scarcely found in our sample of rape events. For
Discussion
Despite the increased reliance on the analysis of forensic evidence to solve crime (Beaver, 2010, Strom and Hickman, 2010), little empirical research has been conducted on the factors related to forensic awareness during the crime-commission process, a detection avoidance strategy especially important for sexual crimes. As was observed in this study, more than half of the rape events of the sample showed some signs of forensic awareness. The most common specific strategies used by offenders had
Author's note
The views expressed are those of the authors and are not necessarily those of the Correctional Service of Canada. We would like to thank the anonymous reviewers for their very helpful comments.
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