Abstract

Evidence retrieved from crime scene helps reveal the underlying motives linked to the crime including the modus operandi, aids the police detectives in linking crime scenes or crime and most importantly, identifying crime suspect/s. Given the complexities that characterise crime scene investigation, detectives have had to rely on technologies to facilitate investigation. Recently, eyetracking has gained prominence in the field of forensic science including psychology. We have developed a new data-driven methodology that directly tracks eye movements to aid police crime scene investigation by examining differences in the Expert’s vs Novice’s eye gaze behaviour when watching videos depicting crime scene. Two groups of participants (n=36) watched violent knife attack in an office environment while their eye movements were being monitored. Group 1, otherwise known as the “Experts” first saw the knife attack in the office setting (Time 1) and two days later saw the same office environment, but without the knife attack (Time 2). Group 2, the “Novice” first saw the neutral office setting (Time 1) and after day two, saw the violent office attack (Time 2). The results revealed differences in gaze patterns made towards the non-violent videos (neutral office setting) with Group 1 (Expert) observers deploying more fixations on the location in the video where the crime occurred compared to Group 2 (Novice) observers, suggesting priming effect. Experts are more likely to attend to relevant and important aspects of the scene and can use knowledge-based shortcuts to understand the scene more easily compared to novices. Our data suggests that fixation patterns may be repeated during the recognition of familiar scenes. Thus, tracking eye fixations could give insight as to whether the suspect under police interrogation is lying about having memory of the crime scene.