Investigative interviews with suspects are complex interpersonal interactions that are focused on eliciting statement evidence to use within subsequent investigative and judicial processes. When conducting an investigative interview, criminal investigators face a series of decision points – involving potentially competing alternatives – which collectively determine how the interview will unfold. These decisions are also made under real-world constraints of limited time and knowledge. Interviewer decision-making, therefore, is both psychologically complex and practically consequential. In the present chapter we examine the role of interviewer decision-making across five dimensions of investigative interviewing: Why (is an interview conducted?), Who (will participate?), When and Where (will the interview occur?), and What (techniques will be used?). We use this structure to outline the current state of the literature on suspect interviewing best practices and how each decision point raises factual and ethical considerations for interviewers, interviewees, and the criminal justice system more broadly. We conclude by discussing potential future directions for research that can continue to inform effective decision-making in this area.

Effective investigative interviewing is at the heart of any police investigation and thus is the root of achieving justice in society. This is because the key aims underpinning any investigation are to: (i) find out what happened, and if anything did happen, (ii) to discover who did what, and (iii) to collect evidence in a way that will be credible to decision-makers. In order to achieve this, investigators need to gather information whose source is usually a person (e.g., a witness, victim, suspect, complainant, first officer at the scene of a crime and so on). Thus, one of the most important tools in an investigator’s toolbox is the ability to interview. This chapter will examine the evidence base examining the most effective methods to interview and assess witness reliability within an investigative context.