Some years ago, I wrote a book about a whaling captain who was a serial killer.
It began with stumbling over a semi-literate journal in very bad shape, which had been written by the cooper of the whaleship Sharon. It was not easy reading, being a rough daybook, revealing little despite the daily entries. But then, suddenly, I was reading a grueling description of the young black steward being beaten to death. By the captain. While the rest of the crew stood by and watched.
It led to a great deal of research, involving a lot of travel and asking a lot of questions that I had never expected to be asking. The plot thickened when I found logs of previous voyages with the same captain -- voyages in which there were unexplained deaths. So, was this captain a serial killer? And, if so, was he a psychopath?
How can you tell if a man or a woman is psychopathic? I found a book called Without Conscience, written by the psychologist, Robert Hare, which contained a fascinating checklist.
The list in full is: glibness and superficial charm, grandiose sense of self-worth, pathological lying, cunning/manipulative, lack of remorse, emotional shallowness, callousness and lack of empathy, unwillingness to accept responsibility for actions, a tendency to boredom, a parasitic lifestyle, a lack of realistic long-term goals, impulsivity, irresponsibility, lack of behavioural control, behavioural problems in early life, juvenile delinquency, criminal versatility, a history of "revocation of conditional release" (ie broken parole), multiple marriages, and promiscuous sexual behaviour.
The scary part is that most people you know display one or two of these characteristics.
Interestingly, a lot of this is echoed in an article by Tom Chivers in the New Zealand Herald, called Born to Kill? An interview with Robert Hare reveals that he is still working away at the problem.