All of which was interesting but not helpful when it came to catching a killer. What Carol – and Paula – needed was something a bit more concrete. ‘You’re not young,’ he said thoughtfully. ‘Bev was in her late thirties and you thought she was a possibility. Which probably puts you between thirty-five and fifty. You’re authoritarian and arrogant, contemptuous of others. You let people know when they don’t come up to scratch, which has probably hurt your career. And that makes you even more resentful. You’re practical. You turn up with a taser and whatever is in that case.’ He paused for a moment then smacked himself in the forehead. ‘Of course. It’s a portable anaesthetic kit. Like paramedics use. You’re putting them under so they don’t make a noise in the boot of the car. That’s what you’re doing.’ He patted his pockets for his phone out of habit. Then it dawned on him he couldn’t call Carol or even text her to share his revelation. Disappointment rippled through him, leaving him frustrated and annoyed.

‘Focus, you moron,’ he chided himself. ‘Just make sure you remember it in the morning. And as for you, you clever bastard – you’re probably in a white-collar job, though not a highly qualified professional. Not a doctor or a lawyer. Maybe a middle-manager of some sort. But you think you’re better than that. That’s why you’re leaving them where they’ll be found. You want us to pay attention, to take you seriously.’

Tony stood up again and walked the perimeter of the room, trailing his fingers along the wall as he went. ‘You’re local. Both your victims are from Bradfield. I think you’re picking them at random. You see them on the street or on the bus and they look right and you stalk them to see whether they’ll do. You acquired and killed Bev very soon after Nadia, which makes me wonder whether you’ve got a little list of possibles.

‘You’ve probably got a house with a garage or a private area for parking cars. You’re taking their cars somewhere, then going back for your own later. Then you dump theirs. We need to find out where those cars end up. Burned out? Left with fake plates in long-term parking? What are you doing with them?

‘The other thing is, you need to be able to contain them. Keep them captive without being overlooked or overheard. No nosy neighbours wondering what the screaming is all about.’

It was thin, he had to admit. But with the limited resources at his disposal, he’d made a start. He was beginning to have a sense of what kind of man this killer was. And if he was right about the portable anaesthetic machine, Paula might be able to develop that into a viable lead.