I know what I’m doing is wrong: I’m violating someone’s private sanctuary. But I only visit houses that have been put up for sale, whose owners are inviting scrutiny. I’m careful never to leave a trace of my presence. I made a promise, and I never break my word.

First do no harm.

For a moment, I consider taking one of the photographs. Mr and Mrs Unmade Bed, with their two children, Boy and Girl. Here they are on their ski break in Zermatt. Oh, look! Boy and Girl have a new puppy, Dog! Look, Dog! Look!

They make family life seem so easy.

In the end I slip one of a pair of dice into my pocket, and go back through the kitchen, leaving via the same back door in the laundry room as I came in.

I even lock it behind me, which is more than the owners remembered to do.

SETtalks | psychologies series

Science ♦ Entertainment ♦ Technology

Inside the mind of a psychopath | Original Air Date 9 July

The transcript below has been lightly edited for length and clarity.

I appreciate the introduction, Ken, but I’m guessing you all know who I am, or you wouldn’t be here.

[Laughter]

I know you’re all desperate to get to the juicy stuff, the Glass House Murders, and we will soon, I promise.

But this talk is supposed to be educational, so let’s kick off with a statistic: one in a hundred normal people – and I’m putting normal in inverted commas here – is a psychopath.

I can see you all doing the maths, so let me save you the trouble. There’s about a thousand of you in this room.

So that means roughly ten of you are psychopaths. But since the stat I just gave you rises to one in twenty-five when we’re talking about business leaders and CEOs, we’ve probably got about forty psychos in here this evening. It could be carnage by the end of the night.

[Laughter]

But let’s get serious for a minute. It’s essential you approach this subject with something other than a pop-culture understanding of psychopathy.

Think of it as Psycho 101. I’ll do my best to make it as painless as possible.

Thanks to Hollywood, when you hear the term psychopath you imagine a knife-wielding maniac with crazy eyes. Jack Nicholson in The Shining, Hannibal Lecter in The Silence of the Lambs, Norman Bates in Psycho. Well, I guess the clue’s in the name with that last one.

[Laughter]

But what about this young lady who looks like Sandra Bullock sitting here in the front row? If you could just stand up – thank you. Lovely sweater, by the way. Looks like butter wouldn’t melt, doesn’t she? The archetypal girl-next-door. But trust me, she’s the one you need to be scared of.

[Laughter]