As part of research for a BBC Horizon documentary What makes a Psychopath?, director Rebecca Harrison met child molesters, rapists, and murderers.
The programme will be an 'in-depth exploration of the psychopathic mind', and will be presented by psychologist professor Uta Frith.
Director Harrison conducted face-to-face interviews with inmates in Indiana State Jail, such as child molester Mark Moye, murderer Ryan Klug, and rapist and murderer Joshua Wright.
Writing for the Daily Mirror, Harrison explained how one interview with a patient referred to only as 'Robert', chilled her to the core.
Robert, a 17-year-old murderer, was said by Harrison to have a 'charming mannerism'.
Sat just a few feet from this man I probably should have felt more frightened of him than I initially did.
But his charming mannerisms sucked me in.
Charisma is a trait often associated with psychopaths.
The spell was broken when Robert recounted with 'relish' the way he had murdered his victim.
According to Harrison, Robert then claimed he could 'read' anybody - based on their clothes, and their posture.
This is how he 'read' Harrison:
You’re on edge a little bit … I’m not a threat…You’ve got dark pants on; you’ve got dark boots on.
Your boots alone are laced all the way tight and your pants are darker of a colour, so you started today with a firm, determined goal.
Your shirt is … more at ease. It’s not a hard colour, its see how the day takes me, I’m going to do this but we’re just going to see how it goes.
Harrison wrote that she did not breathe the entire time.
She asked if Robert considered himself a psychopath.
Not a psychopath.
What Makes a Psychopath airs on BBC 2 at 9pm on 29 August.