Due to my area of expertise, nearly every week I receive queries from students (and sometimes reporters) asking me questions like, can I spot a serial killer? What turns someone into a serial killer?

It seems obvious that anyone who willfully and repeatedly commits murder is a psychopath: remorseless, egotistical, manipulative, and cruel. Think of Ted Bundy, Dennis Rader, or John Wayne Gacy.

New Zealand Prime Minister Jacinda Ardern vowed Tuesday never to utter the name of the twin-mosque gunman as she opened a sombre session of parliament with an evocative "as salaam alaikum" message of ...