Throughout the film, Teddy's narrative is presented as unreliable. He suffers from flashbacks, hearing voices, and exhibits paranoia, which raises questions about the accuracy of his perceptions. As the investigation progresses, Teddy becomes increasingly obsessed with uncovering the truth, driven by a personal connection to the case that he refuses to reveal. His obsession is fueled by a sense of guilt and responsibility, which is slowly revealed through his interactions with Dr. Cawley and the hospital's patients.