Background Several jurisdictions mandate the presence of an independent support person during police interviews with vulnerable people. The current study investigated police officers’ experiences and perceptions of these volunteers during interviews with people with intellectual disability(ies) (ID). Methods The sample comprised 229 police officers who attended a mandatory firearms training course in Melbourne, Australia, in 2010. Results Participants commonly reported utilizing independent support persons and displayed a fair understanding of their role. Overall, volunteers were engaged more frequently than family/friends; police considered the volunteers to be more impartial during interviews, whereas family/friends provided a greater level of emotional support to interviewees. Conclusions Independent support persons need to demonstrate two quite different types of support to people with intellectual disability(ies) during police interviews; these require quite different skill sets and suggest the need for more tailored training and support for these volunteers. Implications for future research and policy are discussed.