Kent Kiehl has studied hundreds of psychopaths. Kiehl is one of the world’s leading investigators of psychopathy and a professor at the University of New Mexico. He says he can often see it in their eyes: There’s an intensity in their stare, as if they’re trying to pick up signals on how to respond. But the eyes are not an element of psychopathy, just a clue.
Officially, Kiehl scores their pathology on the Hare Psychopathy Checklist, which measures traits such as the inability to feel empathy or remorse, pathological lying, or impulsivity.