Guilty and innocent suspects’ strategies during police interrogations

Abstract

Deception detection has largely failed to investigate guilty and innocent suspects’ strategies. In this study, mock suspects (n=82) were interrogated by police trainees (n=82) who either were or were not trained in the technique to strategically use the evidence (the SUE technique). Analyses revealed that guilty suspects to a higher degree than innocent suspects applied strategies in order to appear truthful. Guilty suspects reported diverse strategies, while innocent suspects reported the strategy to tell the truth like it had happened, indicating a belief in the visibility of innocence. The realism in the suspects’ expectation about how their veracity was judged was largely dependent on the way in which they had been interrogated. The truth-telling suspects who were interrogated according to the SUE technique were optimistic about being judged as truthful; this optimism was warranted as the vast majority of them were classified as truthful. The SUE technique seems to help (a) spotting guilty suspects without them being aware of it and (b) spotting innocent suspects, and they become aware of it. That innocent (but not guilty) suspects can read how the interrogator views them is advantageous for the investigative process.

Keywords:

• Innocence
• guilt
• deception detection
• suspects’ strategies
• strategic use of evidence

Acknowledgments

This research was supported by a grant from the Swedish Research Council given to the second author. Thanks are due to Simon Andersson, Katja Dahlqvist, Ola Kronkvist, Sara Landström, Malin Olsson, Anna Rebelius, and Emma Roos af Hjelmsäter for help with the collection and coding of data. Many thanks to Superintendent Royne Nilsson for inspiring us to conduct this research.