Multiple perpetrator sexual assault: A 7-year retrospective review of sexual assault treatment unit cases

This study publishes longitudinal Irish data examining the characteristics of reported cases of multiple perpetrator sexual assault in those attending Sexual Assault Treatment Units (SATUs).

This is a retrospective cohort study of reported multiple perpetrator sexual assault (MPSA) cases in comparison with single perpetrator sexual assault (SPSA) cases, who attended the Sexual Assault Treatment Unit network between January 1, 2017, and December 31, 2023.

During the study period, 6395 cases of sexual assault were recorded where the number of perpetrators was documented. Of these, 502 cases were reported as MPSA, accounting for 7.8% of all cases. Of those who disclosed MPSA, 86.7% were female, 12.7% were male and 0.6% identified as "other." While victims/survivors were more likely to be female, males were overrepresented in the MPSA (odds ratio [OR] 2.01, confidence interval [CI] 1.52-2.66, P < 0.0001) compared with the SPSA cohorts. MPSA victims were significantly more likely to be verbally threatened (OR 2.15, CI 1.74-2.66, P < 0.001) or physically restrained (OR 1.91, CI 1.58-2.33, P < 0.001), and it was more likely for a weapon to be used during the assault (OR 2.60, CI 1.99-3.39, P < 0.001) compared to SPSA victims. MPSA victims were significantly more likely to have a physical injury, including anogenital or extra-genital injury (OR 1.25, CI 1.03-1.52, P = 0.02). MPSA victims were significantly less likely to be assaulted at home (OR 0.63, CI 0.49-0.81, P < 0.001) and significantly more likely to be assaulted outdoors (OR 1.42, CI 1.15-1.76, P = 0.001) than SPSA victims. MPSA victims were significantly more likely to be assaulted by a stranger (OR 2.21, CI 1.83-2.68, P < 0.001) or person in authority (OR 2.13, CI 1.30-3.51, P = 0.002) than SPSA victims. Victims of MPSA were significantly more likely to disclose concern for drug-facilitated sexual assault (DFSA) (OR 1.90, CI 1.53-2.35, P < 0.0001) than victims of SPSA.

This is the first study to characterize MPSA in an Irish setting. It demonstrates findings with clear clinical, forensic, and policy implications. The results might inform national SATU guidelines to improve investigation and care in MPSA cases.