According to popular wisdom, psychopaths are crazed and bloodthirsty serial killers. The reality is not so simple. While many psychopaths do commit violent crimes, not all psychopaths are criminals and not all criminals are psychopathic. Psychopaths are found in many walks of life and are often successful in competitive professions. However they are also ruthless, manipulative and destructive. Equinox reports on techniques developed by psychologists to work out whether a person is psychopathic and shows how brain scientists are coming close to mapping the malfunctions in the brain that cause a person to be a psychopath. In Britain one person in 200 is likely to be a psychopath. However psychopaths are thought to be responsible for half of all reported crimes and to make up between 15% and 20% of the prison population. The programme looks at the most recent research into the brains and behaviour of psychopaths and assesses the prospects for the treatment or containment of this antisocial group of people who create such a disproportionate amount of destruction. Psychopaths who have been convicted of appalling crimes explain with disturbing clarity what motivated them in their violent and destructive behaviour. They speak without shame, guilt, remorse or empathy with their victims. Though they are articulate and, at times, plausible and charming, they lack the range of emotions experienced by the rest of society. They know the difference between right and wrong but they do not feel it. Robert Hare, Professor of Psychology at the University of Vancouver, has devised a system of assessment called the Psychopathy Checklist. In specialised interviews, psychologists assess individuals on a scale of 0 to 40 for a series of character traits, including callousness, superficial charm, lack of empathy and many others (for more detail look at How to recognise a psychopath). Anyone whose score is greater than 26 is diagnosed as psychopathic.