Stalking can be defined as a pattern of targeted, repeated, and unwanted intrusive acts that can be reasonably expected to cause apprehension, distress, or fear. Stalking victims frequently experience a significant psychological harm, and approximately one third are physically assaulted. Given the damage associated with prolonged or violent stalking, key concerns for criminal justice agencies are accurate assessment and identification of those stalkers most likely to continue to stalk, stalk again in the future, or become physically violent. Risk assessment has therefore been a key focus of stalking research, and two structured risk assessment instruments for stalking now exist. This article describes the development of the stalking risk assessment literature, identifies challenges when assessing stalking risks, and reviews risk factors that have been empirically linked to stalking recidivism (reoffending) and stalking-related violence.
Stalking Risk Assessment Research
Identifying risk factors that can be used to predict stalking-related violence has been a central goal of stalking research since the field began in the early 1990s. It was such a focus that in 2007 the prominent stalking researcher, Reid Meloy, described it as the current quest for the Holy Grail. The stalking risk assessment literature developed as the broader literatures on violence, sexual, and general offending risk assessment were flourishing, influencing how stalking risk assessment was investigated and understood. However, it quickly became apparent that there were characteristics unique to stalking that meant existing risk assessment research and instruments were not appropriate for all stalking cases. It took some years to develop a body of research that could inform the development of structured risk assessment instruments specifically for stalking, with the first instruments published in the late 2000s (the Guidelines for Stalking Assessment and Management in 2008 and the Stalking Risk Profile in 2009).
Challenges of Assessing Stalking Risk
There are a range of factors that make stalking risk assessment a particular challenge for researchers and practitioners. The first, and most obvious, difficulty is the diversity of both stalking behaviors and the contexts in which stalking arises. Stalking occurs between former intimates, between neighbors, workmates, strangers, and family members. It can be amorous in intent, or vengeful and aggressive, or both. This makes it extremely difficult, if not impossible, to derive the kinds of algorithmic actuarial risk assessment instruments that were successfully developed for violence, sexual offending, and general offending during the 1990s. Even if large enough samples of stalkers could be collected, it would be impossible to identify a single algorithm, or set of risk factors, among the variations in stalkers and their behaviors.
In addition to its diversity, stalking differs from violent, sexual, and general offending in other important ways:
- Stalking is targeted, and the nature of the prior relationship between the victim and the perpetrator plays a central role in the stalking and likely outcomes.
- The majority of stalkers are not physically violent, but can still cause significant harm to the victim through their intrusive and relentless behavior, meaning that stalking risk goes beyond physical violence.
- Stalking involves behaviors that would otherwise be considered nonthreatening and nonviolent, possibly rendering risk factors for physical violence unrelated to future stalking.
- Stalking is by definition persistent with risk toward a specific victim possibly fluctuating over time, even while risk to other people is low.
In their seminal 2002 article, Canadian psychologists Randall Kropp, Stephen Hart, and David Lyon noted that these characteristics were inconsistent with most of the extant literature of violence risk assessment. This literature ignored the relationship between the victim and the perpetrator, examined only the likelihood of physical harm, and followed up discrete outcomes over a relatively limited period. They recommended that given the unique nature of stalking risk, structured professional judgment approaches would be useful and went on to develop the Stalking Assessment and Management with this in mind.
A subsequent 2006 article published by a group of Australian researchers and clinicians elaborated further on these issues. This group of authors suggested that one way of dealing with some of these challenges was to change how stalking risk was conceptualized. Rather than assessing the risk of stalking in a particular case, they suggested that it is more useful to think of stalking as a behavior that presents different kinds of risk to the victim, including psychological, social, or physical harm if the stalking continues or recurs and/or escalates to physical or sexual assault. With this framework, each type of outcome could be investigated and specific risk factors identified. This perspective strongly influenced the same authors’ subsequent development of the Stalking Risk Profile.
Stalking Risk Assessment Research
There are now dozens of studies examining risk factors for a wide variety of different outcomes in stalking cases. Nevertheless, in comparison with the general violence or sexual offending risk assessment literature, research on stalking risk remains relatively limited, meaning that conclusions must be drawn cautiously. Moreover, the majority of risk factors identified in existing studies are static, or unchangeable, historical characteristics such as past violence, which are not particularly helpful to risk management. Future research examining more nuanced risk factors is needed to better target treatment that can reduce the risk of future stalking or stalking-related violence.
Examining Risk Factors for Future Stalking
Future stalking may involve continued stalking of the current victim (or if the stalking has ceased, recommenced stalking of the same victim) or the risk of future stalking of a different victim. Due to the lack of research, however, the empirical evidence for risk factors for these outcomes is relatively weak.
Unlike research related to stalking risk factors, some information about relevant risk factors can be gleaned from the small body of research examining stalking recidivism. The first study of this kind was published in 2003 and used a sample of 148 U.S. stalkers who were followed up between 2.5 and 12 years after a court assessment, predominantly using criminal justice records. In total, 49% of the same reoffended with further stalking, 80% within a year of the initial assessment. The strongest predictor of stalking recidivism was the presence of a personality disorder, particularly the presence of antisocial, narcissistic, or borderline personality traits. The combination of a personality disorder and substance abuse at the time of the original assessment also contributed significantly to recidivism, as did having a prior intimate relationship with the original victim. Aspects of these findings have been replicated in other studies: Personality disorder or problematic traits were also linked to multiple stalking episodes in two Australian studies (2012 and 2017), each involving a sample of approximately 150 forensically involved stalkers. Other risk factors for future stalking include the nature of the prior relationship between victim and stalker and the perpetrator’s criminal history. A large study of over 1,000 stalkers from North America reported that former intimates were more likely to reoffend than those with other kinds of relationships to the index victim. The presence of a criminal history was linked to stalking recidivism in two studies, the first a 2009 Dutch study and the second from Canada in 2011, using quite different forensically involved samples. The Canadian study also identified a history of mental health diagnosis as a risk factor, although the relationship was weak and requires further investigation.
Only one Australian study (published as a thesis in 2015) has been able to differentiate between risk factors for future stalking of the same versus a different victim. Information from police records of 160 Australian stalkers showed that 28% were charged with further stalking offenses over an average 5.5-year follow-up period. Of these, 56% reoffended against the original victim and 56% against a new victim (6% stalked both the same and a new victim), with significantly shorter time to reoffending involving the same victim (estimated mean time of 40 weeks vs. 108 weeks). When examining any stalking recidivism, personality disorder or problematic traits were again related to recidivism, as was a history of stalking prior to the episode that led to their assessment for the research (the index episode). Duration of the index episode was also linked to subsequent stalking charges, with stalkers who had already persisted for more than 6 months having almost 3 times greater odds of reoffending.
This 2015 Australian study also examined risk factors for reoffending against specific stalking victims, with marked differences in the predictors identified. Stalkers who reoffended against the same victim were significantly more likely to be male, to have problematic personality traits or disorder, an index stalking duration of greater than 6 months, and to have approached the victim during the index stalking episode. In subsequent multivariate models, major mental illness was also shown to be important to predicting this outcome. None of these risk factors were related to reoffending against a different victim. Instead, a history of prior stalking, a criminal history, and being a stranger to the stalking victim were significant predictors. These findings suggest that different risk factors may, in fact, be related to future stalking of the same, versus a different, victim. Further research and replication of these results are required to provide evidence-based risk assessments of future stalking.
Examining Risk Factors for Stalking-Related Violence
In contrast to the limited literature on the risk of future stalking, by 2000, there were more than a dozen published studies investigating risk factors for physical violence during a stalking episode. A meta-analysis of 13 studies involving 1,159 individuals was published in 2004, with an overall rate of physical violence by stalkers of 38.7%. The presence of threats, substance use by the stalker, the absence of a psychotic disorder, a history of violence, and a prior intimate relationship between victim and stalker were all positively correlated with physical violence during the stalking episode.
These findings were replicated a decade later in an expanded meta-analysis of 25 studies with over 5,000 participants. The overall rate of physical violence in this larger sample was similar, 35%. Strengthening and expanding the findings of the earlier review, the newer analysis identified prior intimate relationship, threats, perpetrator substance use, absence of psychosis in the stalker, and stalker history of violence as risk factors for perpetrating stalking violence. In addition, stalker personality disorder, criminal history, and male gender were identified as risk factors. These meta-analyses provide strong evidence that stalking-related violence is most commonly committed by former intimates who have a broader range of antisocial characteristics and engage in a range of problematic and criminal behaviors in addition to stalking.
Risk factors such as those identified in the meta-analyses, while useful for prediction at the group level, are not always useful for assessing risk in individual cases or designing clinical interventions to reduce risk. Stranger and acquaintance stalkers are occasionally violent, as are psychotic stalkers, making risk assessment a nuanced and challenging task. The two structured risk assessment instruments developed to assess the risk of stalking-related violence attempt to assist with this process. They both include a range of other, more dynamic, risk factors such as the presence and intensity of anger toward the victim, irrationality or distress on the part of the stalker, and consideration of the pattern of stalking behavior. While they are drawn from the broader stalking and violence risk assessment literatures, the empirical relationship of these risk factors to stalking violence is yet to be specifically evaluated and should be the focus of future research.
References:
- Kropp, P. R., Hart, S., & Lyon, D. (2002). Risk assessment of stalkers: Some problems and possible solutions. Criminal Justice and Behavior, 29, 590–616. doi:10.1177/009385402236734
- McEwan, T. E., Daffern, M., MacKenzie, R. D., & Ogloff, J. R. P. (2017). Risk factors for stalking violence, persistence and recurrence. Journal of Forensic Psychiatry and Psychology, 28, 38–56. doi:10.1080/14789949.2016.1247188
- McEwan, T. E., Mullen, P. E., & Purcell, R. (2007). Identifying risk factors in stalking: A review of current research. International Journal of Law and Psychiatry, 30, 1–9. doi:10.1016/j.ijlp.2006.03.005
- McEwan, T. E., Ogloff, J. R. P., & Pathé, M. (2011). Advances in stalking risk assessment. Behavioral Sciences & the Law, 29, 180–201. doi:10.1002/ bsl.973
- Mullen, P. E., Mackenzie, R., Ogloff, J. R., Pathé, M., McEwan, T., & Purcell, R. (2006). Assessing and managing the risks in the stalking situation. Journal of the American Academy of Psychiatry and the Law, 34, 439–450.