Content Warning: This text and the guide discuss murder.

Bryan Kohberger, the main suspect in the four real-life slayings in When the Night Comes Falling, was, coincidentally or not, an avid student of forensic psychology. This hybrid of psychology and criminology uses the scientific method to study the human mind as it relates to crime, punishment, and the justice system in general. During his graduate studies, Kohberger came to idolize one of his professors, Dr. Katherine Ramsland, a forensic psychologist with a special focus on the psychology of those who kill. Kohberger’s connection to and interest in forensic psychology—more specifically, Ramsland’s serial killer-specific research—placed him in close contact with information that helped him evade discovery long after his crime and gave him the confidence to initially kill. The subject is emphasized throughout the book because of the interests/careers of Bryan, Ramsland, and the author, Howard Blum.

One aim of forensic psychology involves criminal profiling, i.e., inferring, from crime scene evidence, a psychological and behavioral “sketch” of the (unknown) perpetrator that can be used to narrow the police’s search. In her work, Ramsland cautions that serial killers display a wide spectrum of personality types: There is no universal psychological profile.