“I knew I wasn’t going to convince them,” I told Judy finally. “What was it that someone said? In order to understand me, you have to agree with me. For the police, the most important aspect of the case is that it’s closed and a line has been drawn under it. They don’t care about truth; it’s a matter of statistics. If they reopened the case and solved it, their statistics would look the same as they do now, except that they would have done a great deal more work.”

Judy looked at her watch.

“I’m sorry,” I said. “Am I boring you?”

“I was going to say that our time is up,” she said. “I make it a rule to be very strict about that. I find it’s helpful if the participants know that the time is limited. But just this once I’m going to continue for a few minutes. What did the detective say?”

“He said lots of things, all negative. He looked carefully at my charts and then he called for another detective to come and look at them as well, but I think that wasn’t because he found them interesting or convincing. It’s more likely that he thought it was all so bizarre that someone else needed to witness it so they wouldn’t think he was making it up when he told them about it in the pub later. What he said was the sort of thing that people have been saying all along. Namely, that I haven’t proved Greg and Milena weren’t having an affair. I’ve just proved they weren’t on those particular days. And then he said that maybe they weren’t having an affair, and if they weren’t he hoped that would be of some comfort to me.

“We had a bit of an animated discussion about that. I said I hadn’t even found evidence that they knew each other. He said if it came to that, they didn’t even have to have known each other. They might have met for the first time that day. He might have given her a lift for no reason at all. I tried to point out that there was a problem with that: there was a note from Milena to Greg, which I had found in Greg’s possession, about a sexual encounter on a day when they couldn’t—absolutely couldn’t—have had one. Didn’t he think that was a problem?”

“What was his response?” asked Judy.

“You’re a psychologist,” I said.

“Actually I’m a psychiatrist.”

“It’s the same thing.”

“Well . . .”