Elien Neimeijer

96 Method Participants and setting This study was conducted at Trajectum, a secure forensic treatment facility for adults with MID-BIF and externalizing behaviour problems (i.e., aggression or sexual offens- es) and/or internalizing problems (e.g., self-injurious behaviour and suicide attempts), located in the northern and eastern part of the Netherlands. The study consisted of 212 participants who had MID-BIF (78% male, M age = 41 years, SD = 12.6). An IQ score was available for 183 participants: 47% of the participants had a mild intellectual disability (IQ 50-69) and 53% had borderline intellectual func- tioning (IQ 70-85). Mean total IQ was 69.7 ( SD = 9.7). Besides MID-BIF, participants had severe challenging behaviour and/or a history of substance use. Most of the participants were admitted because of externalizing behaviour problems (i.e. aggressive behaviour or a sexual offense) and/or internalizing problems (e.g., self-injurious behaviour or suicidal behaviour). Participants were placed in the facility under criminal law (42%), civil law (24%) or were voluntarily admitted (34%). The participants represented 58 living groups. These living groups consisted entire- ly of males (26%) or mixed gender (74%). Living groups are characterised by different levels of restrictions and levels of security, therefore participants resided in living groups with different security levels; 63% of the participants resided in a low security living group, 16% of the participants resided in a medium security living group and 21% of the participants resided in a high security living group. Living groups also differ on care intensity: 24% of the participants resided on a low care intensity unit, 24% on a low to medium care unit, 24% on a medium care unit, 22% on a medium to high care unit and 6% resided on a high intensive care unit. A total of 262 staff members (49% male) of the same 58 living groups also participated in the study. The age of the staff members was 37.2 years ( SD = 11.34). The majority of the staff had worked longer than four years at the organisation (38% between 4-10 years; 23% more than 10 years). One-third of the participants had worked less than two years at the organisation (10% less than 1 year; 8% between 1-2 years; 13% between 2-4 years; 8% unknown).