Becky followed the DI into the kitchen, where the smell was worse. The remains of an Indian takeaway, several days old, sat on the table, and the sink was piled high with pots.

‘Sorry,’ she said. ‘This is turning my stomach. Is it okay with you if I open the back door?’

‘Of course. Let me,’ he said. ‘This door leads to the rear porch. There’s a toilet there too. I’ll open up so we can get some fresh air. It will be cold, though.’

Becky shuddered. ‘Rather be cold than sick, if that’s okay with you.’

The DI cast her a worried glance as he left the room. She heard him open the back door and he reappeared, rubbing his hands together.

Becky pulled her coat closer around her, but felt much better for the cold blast of fresh air.

‘If you don’t feel too good, it’s okay to use the loo down here. Everything’s been processed.’

‘No, I’m fine,’ she said.

What she didn’t want to admit to was that it wasn’t just the smell in here that was getting to her; it was the sight of the blood.

I can’t move. They are out there, in my kitchen. The tiny room I am standing in is less than three metres away from two police officers and one of them isn’t feeling well. I’m going to be caught.

Would it be better to walk out and give myself up? I don’t know. All I do know is that my chest feels as if it is in a vice. I gently let go of the handle of the toilet chain and wrap my arms round my waist, trying to hold myself together. They are talking, and I can hear every word.

‘There was a massive argument the day before the incident, as we understand it. Caroline – everyone calls her Callie – was screaming at him. Neighbours said she appeared almost deranged.’

I close my eyes. He is right. I had felt as if I was going to explode that day – as if all the blood had literally rushed to my head. I remember catching a brief glimpse of myself in a mirror, my face flushed bright red, my eyes dark, practically demonic.

‘What do we know about him – Ian Fullerton?’ the woman asks.

‘He’s got previous. Assault on a woman he lived with a couple of years ago. She withdrew her complaint in the end, but it was nasty.’

I almost make a sound. Ian never told me that. But why would he? Once again the risks of meeting someone with whom you have no shared connections jump out at me.

‘He sounds like a charmer,’ the woman says. ‘Anything else?’

‘He’d recently sent her a lot of very abusive emails. Certainly enough to cause a major argument that could have turned nasty.’