Eliciting admissions from suspects in criminal investigations

Sammanfattning: The psycho-legal literature is scarce with respect to specific interviewing tactics aimed at eliciting new and critical information (admissions) from suspects in criminal cases. The first major aim of this thesis was to fill this void by introducing and testing a novel evidence disclosure tactic, called the SUE-Confrontation, which draws on the general principles underlying the Strategic Use of Evidence (SUE) framework. The comparative efficacy of the SUE-Confrontation interview was examined in a series of laboratory-based studies. In addition, a number of dependent measures was used to test the relationships between the principles behind the SUE framework. The participants either committed a mock crime (guilty) or performed equivalent noncriminal activities (innocent) divided into three phases, after which they were interviewed as suspects. The interviewer possessed evidence pertaining to two (less critical) phases of the crime, but lacked information about the third and more critical phase. For the SUE-Confrontation interview, the interviewer initially aimed to obtain verbal cues to deceit (statement-evidence inconsistencies) by using the evidence strategically. Thereafter, the interviewer used these cues (confronted the suspect with his or her inconsistencies) to elicit admissions about the critical phase for which the interviewer lacked information. In Study I (N = 120), the SUE-Confrontation interview was compared to two control interviews: Early Disclosure of Evidence and No Disclosure of Evidence. As predicted, the innocent suspects (compared with the guilty suspects) were more forthcoming regarding their activities related to the critical phase. No difference was found between the interview conditions with respect to the guilty suspects’ forthcomingness regarding the critical phase. Nonetheless, the results were promising in terms of eliciting admissions through strategic interviewing. For Study II (N = 90), the interview protocols were revised. As predicted, the guilty suspects in the SUE-Confrontation condition (compared with the Early Disclosure and No Disclosure conditions) perceived the interviewer to have had more information about the critical phase and disclosed more admissions about this particular phase. In Study III (N = 75), the aim was to improve the ecological validity of the tactic by providing the suspects with the opportunity to explain the discrepancies in their statements (labelled the SUEConfrontation/ Explain condition). The guilty suspects in the SUE-Confrontation (following the same protocol as used in Study II) and the SUE-Confrontation/Explain conditions combined (versus the Early Disclosure condition) overestimated the amount of evidence that the interviewer possessed about the critical phase. The SUE-Confrontation/Explain condition did not differ from either the SUE-Confrontation condition or the Early Disclosure condition with respect to the number of admissions made by the guilty suspects. Importantly, the SUE-Confrontation interview resulted in more admissions than the Early Disclosure interview. The second major aim of this thesis was to explore police officers’ planned use of the available evidence to elicit admissions. Study IV was designed as a survey study in which police officers (N = 69) planned an interview with a suspect in a fictitious murder case. The investigators planned to disclose the evidence more often in a strategic manner (i.e. obtain the suspect’s statement and/or exhaust alternative scenarios before revealing the evidence) than in a non-strategic manner (i.e. reveal the evidence before requiring an explanation). It was rare that the investigators planned to use the evidence pertaining to the less critical phases of the crime so as to elicit admissions about the critical phase (about which they lacked information). Taken together, this thesis demonstrates the development of, and support for, an effective evidence disclosure tactic for eliciting admissions from suspects. Furthermore, the findings lend support to the predicted relationships between the principles underlying the SUE framework. These principles can be tailored to meet the needs of an interviewer, and may be utilised in different criminal cases. Lastly, it is recommended that the SUE-Confrontation tactic be included as part of police officers’ training on how to effectively conduct interviews with suspects.