What’s he doing here? He saw the police artist’s sketch in the paper, helpfully identified himself and has been eliminated from the investigation. Alibis for all five murders, all solid, I recite to myself. His role in the proceedings is well and truly over. He shouldn’t be striding purposefully up the steps of the police station like a man with something urgent to say to a detective.

I run across the car park, mount the steps two at a time, and burst in through the doors after him. If he turned, he’d see me, but he’s busy at the reception desk. I hear the end of his request: ‘… talk to someone involved in the, er … the investigation. Is that possible?’

Why? Don’t give him what he wants: make him explain himself.

‘I mean, it’s not at all urgent. It’s something that … well, it’s awkward. I probably shouldn’t be here at all.’

Oh, God, his voice.

For Christ’s sake, Tribbeck, it’s just a voice. Imagine it coming from the mouth of someone with yellow toenails and dandruffy shoulders.

‘Come with me.’ A uniformed officer wearing a badge with a strange name on it – Zlosnik, I think it said – leads Niall Greeves away from reception into the same corridor I walked along with DC Gibbs nearly two weeks ago. It feels more like a hundred years. As he and Zlosnik shrink with distance, I notice that Greeves is protesting. The closer he gets to the detectives he came here to see, the more he’s changing his mind.

I fight the urge to scream. Anything he knows, I deserve to know before anyone else. No one would be aware of his existence if it weren’t for me.

Could he be Billy? The police are certain he isn’t.

Please let him not be Billy. Not that it’s any business of mine. Just … for his sake, it’s better if he’s not a serial killer. The same would apply to anyone.

A uniformed policeman walks in from outside, holding a sheet of paper in front of his face. Unaware of my presence, he rams into me. ‘Watch it!’ I say.

‘Sorry! So sorry – are you all right? How clumsy of me!’

‘I need to see Sergeant Charlie Zailer. Can you find her for me?’

‘I can’t, I’m so sorry. Got to run. I’m in the middle of something urgent.’ He holds up the piece of paper. It’s an advertisement for a job. I read the words ‘permanent position’ and ‘remuneration’ before he snatches it away and moves on.

He’s almost out of the reception area by the time I manage to say, ‘Hold on a minute.’

He stops with a sigh that I’m not supposed to be able to hear.

‘You’re in a hurry to apply for a job?’