You remember Scott Peterson who killed his wife Laci and unborn child? Everybody said he was such a nice reliable young man. Some children have a knack for discovering how to please, and everybody likes them. Sometimes such children develop as unique Pleasers. That is what they live for: approval, until one day they have forged a personality that they present to the world and they have no idea who they really are.
It is like they have developed an outside envelope at such a price that there is nobody inside: no plan, no guidelines, no empathy, no principles, not much emotion, little feelings. Some rotten trees are like that: only the bark holds them up. They remain unnoticed for a long time amongst other trees.
There is lot of that in the Madoff couple: Mr Madoff did not even invest for his clients at all: his swindle was deliberate from the get go. It makes him a very different guy from somebody who started lying after his affairs went south. That is the difference between a psychopath and a dishonest man. Mrs Madoff was probably all about appearances too: she had a ghost writer for a cookbook published under her name because it was "fun". So the Madoffs were a couple united by their outside shell.
How do you discover that somebody is a psychopath? You cannot: all the external signs are fooling you. Unless of course, you have been victimized before: then you learn to pay attention to all the small signs that tell you if there is a person inside.