Certain violent offenders—especially sexual homicide offenders (SHOs)—have been reported to engage in specific acts at the crime scene that are unnecessary to successfully commit the crime but may serve a psychological need for the offender (e.g., sexual gratification). In studies of sadistic sex offenders—many of whom had killed their victims—the rate of cases where the offender involuntarily inserted an object into any orifice of the victim (foreign object insertion, FOI), reported to be as high as 40% to 65% (Dietz et al., 1990; Warren et al., 1996). However, studies looking at homicide cases generally reported rates as low as 1% (e.g., Keppel, 1995). For instance, the study by Horning et al. (2015) identified only two cases out of 302 homicides. In studies conducted specifically on sexual homicide cases, rates of FOI have varied between 11.4% (40/350; Beauregard & Martineau, 2013) and 23.6% (Chopin & Beauregard, 2020; Koeppel et al., 2019; Safarik et al., 2002; Schlesinger et al., 2010). Partly due to the low frequency of this behavior, limited empirical research has been published on this topic. Moreover, many findings on FOI are anecdotal, stemming from case studies or biased samples (e.g., with overrepresentation of sadistic cases).

It has been suggested that FOI was associated with mentally ill offenders, unplanned homicides, disorganized crime scenes, and an absence of control over the victim (e.g., Douglas et al., 2013). However, more recent research looking at extensive samples of cases involving FOI have questioned such claims and highlighted the association with sexual deviance and sadism (e.g., Koeppel et al., 2019). 

The most extensive study to date on FOI was by Koeppel et al. (2019). Looking at 260 cases of sexual homicide (207 nonserial and 53 serial) from the FBI Behavioral Analysis Unit, they described several aspects of FOI that were not systematically reported previously. They found that a total of 65 objects were inserted, the most common specific categories being tools (e.g., screwdriver) and natural materials (e.g., sticks, logs, rocks). Other objects were weapons (e.g., knife, gun, axe), clothes (e.g., shirt, sock, underwear), and food (e.g., pickle, carrot, ketchup). The largest category of objects inserted though was labeled as “miscellaneous” and included umbrella, chair leg, garbage bag, cutoff genital of victim, soap, beer bottle, toilet brush, baby wipes, and cigarette. Despite the wide variation among these objects, the authors classified 55.4% of them as being phallic-like.  Koeppel et al. (2019) also determined that in the majority of cases of FOI (67.6%), the object was obtained at the crime scene. Interestingly, in only 31.8% of cases FOI was visible at the crime scene, the rest being discovered by autopsy. Contrary to early work on FOI, Koeppel et al. (2019) found that almost half of the FOI were premortem.

Interestingly, FOI has been associated with cases of sexual homicide of older victims. In their study on elderly sexual homicide, Safarik et al. (2002) found that as well as being victims of vaginal (65%) and anal (24%) penetration, victims were also subjected to FOI (22%). Moreover, in their study comparing sexual homicide cases of elderly and adult victims, Chopin and Beauregard (2020) found that the use of restraints, postmortem sexual activity, and FOI were more often perpetrated when victims were elderly (23.2% for elderly versus 8.1% for adult victims).

The current study aims to shine a new light on sexual homicide cases involving FOI by examining the offender, victim, and crime characteristics associated with this specific behavior. Although there is some research on the prevalence and nature of FOI in sexual homicides, there is very little on the characteristics of cases where FOI occurs, and no previous research has compared cases with and without FOI. Given the lack of research on FOI in general and the dissemination of untested ideas regarding the correlates of this behavior specifically, the current study aims to shine new light on sexual homicide cases involving FOI by examining the offender, victim, and crime characteristics associated with FOI. Using a sample of 662 cases of sexual homicide, chi-square and logistic regression analyses were used to compare cases with and without FOI. 

Results of this study showed that offenders who experienced sexual dysfunction and victims who used alcohol/drugs prior to the crime were more likely to be involved in cases with FOI. Cases where victims were beaten, vaginal/anal fisting acts were perpetrated, and mutilation of genitals were observed, were more likely to show evidence of FOI. findings suggest that sexual homicides where FOI was observed indicate the presence of sadism. This sadism is evidenced in the targeting of specific victims (i.e., elderly, vulnerable), acts of penetration involving pain (i.e., fisting), mutilations (i.e., to cause pain as well as to potentially avoid detection), and with the use of specific strategies to avoid police detection. Finally, postmortem sexual activities and the use of strategies by offenders to avoid police detection were also more likely to occur in sexual homicide cases characterized by FOI. These findings are discussed in light of the literature on sexual homicide, the vulnerability of victims, and the manifestation of sadism. Practical implications are also discussed.