Have you watched too many true crime shows and think you could spot a psychopath on your own? Well, this new study might help out your wannabe detective career. 

We already know that psychopaths often exhibit the notorious "psychopathic stare," as per Dr. Robert Hare, the psychologist who created the Hare Psychopath Checklist. Another curious sign is that their pupils don't dilate when they see scary or gory images, and they tend to hold eye contact for an uncomfortable amount of time. 

A new study might just add another item to the list. Researchers from the University of New Mexico and the Mind Research Network interviewed 507 participants from a location that ensured a population of certified psychopaths: prison. 

With the help of AI, the researchers studied the head movements of 507 inmates while they were speaking. Paired with each inmate's results in the Hare Psychopath Checklist, the researchers found that the inmates who were classified as psychopaths barely moved their heads when talking. They described the correlation as "robust and significant."