Analysis: If not stopped, Webster could have become a serial killer

It's almost like you're detached from the normal things that would inhibit somebody who has got feelings not to do that, like a conscience or a sense of morality. There has to be something seriously disturbed with this person to think they can do this. But having done it once and gotten away with it, that's a green light.

To that person, it becomes normal - it's OK. They think if no-one has pulled them up on this, then it must be OK. They're devoid of morality.

It becomes a means to an end. Whoever he is with becomes a pawn in the game. They're almost irrelevant, they cease to be a human being and just become a counter on a deck. He would be the sort of person who would be the least able to be rehabilitated. If it's someone who is committing a crime because they're high on drugs or they're taking drugs because they're unhappy for all sorts of reasons, or if it's something that's happened in the heat of the moment, those are things you can work on.

But with someone who is this premeditated and calculated, you're talking about somehow trying to reconnect them with their emotions and their conscience. When it's not there that's a very difficult thing to try and do. You have to be completely devoid of that to be able to contemplate not only doing this once, but repeatedly.

You have to ask why anyone would have as little conscience or empathy or guilt. These are the normal things that would not only stop people thinking like that, but would actually stop someone doing it even after they thought about it.

Those qualities are learned. You have to wonder what has happened to Malcolm Webster in his life, particularly in his childhood that he hasn't learned those basic human qualities. Why have those basic human qualities not been instilled in him and nurtured in him?

• Elie Godsi is a consultant clinical psychologist and author of the book Violence and Society. He has given evidence as an expert witness in criminal trials, including murders.