‘On the whole, it was easier than I had expected. Only once did I feel myself at risk. That was when the Inspector suddenly intervened. He said in a harsh voice: ‘He married your wife, didn’t he? Took her away from you some people might say. Nice piece of goods, too, by the look of her. Didn’t you feel any grievance?’ I had been expecting this question. I knew exactly what I would say.’ The late, great P.D. James takes us inside the mind of a murderer.