‘And you’re sure you’ve got everything you need?’ Kate asked, pacing the room.

‘Certain, ma’am,’ Laura replied, resting her hand on the thin paper folder in front of her. ‘We know he wasn’t at the Marriott in Colchester. I just need him to admit where he was.’ She glanced up at Patel who was nodding beside her.

‘Has he called for a brief?’ Kate asked.

‘He’s requested the support of the duty solicitor,’ Laura replied. ‘She should be talking to him now.’

‘And what about the forensics? Any word from SSD yet?’

‘No word from them yet. They said they’d phone when they’ve finished testing the samples taken from the second car. We already have his DNA in the BMW.’

‘It’s hardly a smoking gun. Patel, are you happy supporting Laura in the interview?’

‘I agree, ma’am. Isbitt’s our guy.’

‘Although we have the bag he used to suffocate them, his DNA wasn’t on it. We don’t have anything concrete to put him at the second scene, so we’re going to be reliant on a confession to charge him. Are you confident you can get it?’

‘I won’t let you down, ma’am.’

Kate dismissed them, and made her way to the viewing booth so she could watch the interview unfold via the inbuilt cameras in the interview suite. She desperately wanted to be in the room with them, so she could directly influence the questions being asked of Isbitt, ready to pounce on any weakness or slip-up. But she was already taking a big chance even observing it. She had to trust her team and their training. Fixing herself a large mug of coffee, she switched on the screen, just as Laura and Patel entered the room.

‘I need to consult with my client,’ the solicitor demanded.

Kate had crossed paths with her several times before and the woman had done little to endear herself. Wearing a dress suit a size too small, Cindy Everidge had as much respect for the police as Kate had for her.

‘It’s okay,’ Isbitt piped up. ‘I’ve done nothing wrong. I just want to get this over and done with as soon as possible. It’s already been a long day.’

Kate smiled to herself as Laura and Patel took their seats across the table from him. Laura started the recorder and introduced everyone in the room, before reminding Isbitt he was under caution. ‘Should I call you Gavin, or would you prefer Mr Isbitt?’

‘Mr Isbitt.’

‘Good, okay, Mr Isbitt, before we begin I want to remind you that you’re well within your rights not to answer any of my questions, but I would encourage you to do so. I want to hear your side of the story. I’m not here to trip you up or trick you. You understand that, don’t you?’

Kate saw him briefly glance at the solicitor before nodding.

‘Can you verbally confirm that for the tape, Mr Isbitt?’ Laura said.

‘Yes. I understand.’

‘Good. Can you start by telling me where you were on Tuesday night?’

‘Tuesday night? Is that what this is about? The car? I told you on Friday, it was stolen while I was asleep at home.’

Kate could see Laura working through her nerves. ‘I know you’ve already informally discussed what happened to your BMW, but now we need to do so for the record. So, for the tape, please talk me through the events of Tuesday night. Try and be as specific as you can with timings.’

Kate watched Isbitt nervously glance at the solicitor again, before shaking his head in frustration. ‘As I said before, I drove home from Cornwall, arriving at my house around eight o’clock. I went in and chatted with my wife, had a large glass of red wine, and headed up to bed around ten o’clock. I woke at six the next morning, showered and dressed, and when I went to get into my car, I saw it was missing.’

‘And that’s when you reported it stolen?’

‘Yeah. I called you lot, and they said they would send someone round to fill in a report. I said they’d have to come later as I had a meeting with a client, and ended up calling a taxi to get to the meeting.’

Kate had written a list of questions she wanted Laura to ask, and so far, she was sticking to the running order. ‘Does your wife not have a car you could have borrowed?’

‘She does, but she needed it to take my son to the doctor’s.’

‘Your car was relatively new, wasn’t it?’

‘It wasn’t my car. I leased it from an agency. It was for business.’

‘But it was new, right? It had a 17 plate.’

‘What’s that got to do with anything?’

Laura paused. ‘It would be difficult to break into and drive away.’

‘Yes, but as I told you, my keys were missing too.’

‘That’s right. You have a theory about how the thieves got your keys, don’t you?’

‘One of my neighbours had his car stolen the other week. The police reckoned they’d used a wire coat hanger to hook his keys through the letterbox. It was probably the same thieves who took my car.’

‘The thing is, Mr Isbitt, in those types of crime – which aren’t uncommon – the thief will often require several attempts to actually hook the keys and remove them from the property. And what we often find is tiny scuff marks or scratches around the edge of the letterbox where the hanger has caught it. I had a look at your letterbox earlier today, and couldn’t see any scratch marks at all. You haven’t replaced your letterbox since Wednesday morning, have you? Before you answer, I’ll remind you you’re under caution, and that if you have replaced the letterbox, we’ll need to see a receipt for the new one.’

Kate clenched her fist in satisfaction. To illicit a confession, Laura and Patel would need to shed enough doubt on his version of events, before questioning the entire statement.

Isbitt looked glumly at his solicitor. ‘No, I haven’t replaced it, but that doesn’t mean that’s not how they got the keys. Maybe the thief who took them was a bit of an expert at hooking keys? Or maybe he got lucky and hooked them on his first attempt? I dunno.’

Kate recognised the desperation in his voice, and was pleased when Laura removed a photograph of Helen Jackson from the folder and slid it across the table. ‘Do you recognise the woman in this photograph?’

Isbitt took a quick look and shook his head. ‘No.’

‘Are you sure, Mr Isbitt? This is the woman we found beaten and suffocated in the boot of your stolen BMW. Are you sure she doesn’t look familiar?’

He was biting his nails. ‘I don’t know her.’

‘Your wife informed us she took a pill for her migraine on Tuesday night and cannot recall if you were in bed with her all night. I put it to you, Mr Isbitt, that you were the person driving your car, and that it was you who killed Helen Jackson and left her in the boot of your car.’

‘That’s ridiculous!’ he shouted. ‘I didn’t even know the woman.’

Anger and denial were common when suspects felt the walls closing in around them. Kate took a short breath, waiting for the inevitable slip to unfold on the screen.

‘What about last night, Mr Isbitt?’ Laura continued. ‘Can you confirm for the tape where you were?’

‘I’ve told you: I was in Colchester.’

Kate saw Laura slide a second sheet towards him.

‘What’s this?’

‘This is a satellite map showing cellular activity. The green spot represents the signal from your mobile phone, taken from 10.00 p.m. last night. The red spot is Colchester. Note the distance between the spots.’ She passed him a second image. ‘This is the same map, but we’ve zoomed in on the green spot. Tell me, Mr Isbitt, if you were in Colchester all night, why was your mobile phone just down the road in Portsmouth at 10.00 p.m.?’