Credibility and investigative interviewing

Effective investigative interviewing is at the heart of any police investigation and thus is the root of achieving justice in society (e.g. Milne & Bull, 2016). As we outlined more than two decades ago (Kebbell & Milne, 1998) 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 (Milne & Bull, 2006). Investigative interviews, however, conducted by the police can vary greatly in purpose, scope and content. Nevertheless, the common objective of all investigative interviews is to elicit the most accurate, detailed and relevant account from an interviewee. Furthermore, once evidence is collected there is a need to establish credibility. Credibility can be broadly defined as a judgment concerning the quality and veracity of evidence. In a forensic context, judgments of credibility are often of critical importance
because of the frequency of disputed accounts. For example, a woman might say she was raped by a man who in turn says she is lying or a shopkeeper may say a particular woman robbed him whilst the accused says he is mistaken it was someone else. In both these situations, the credibility of the accounts that are given need to take into account whether an individual is being deliberately deceptive or the individual is possibly mistaken. Of course, it is possible for an individual to be both deceptive and mistaken. This chapter will firstly set the context by reviewing the origins and chart the developments in investigative interviewing. Thereafter we will delineate the method employed in effective investigative interviewing, present some evaluative evidence, and finally discuss some of its applications.