‘You’re bullshitting me,’ Waddington said, but his face was freighted with anger at the apparent betrayal. The solicitor looked up, wondering what he had missed.

‘Jason, I’m asking you again. Can you explain why your DNA is on the lapel of Mrs Roy’s coat?’

The prisoner closed his eyes, and wiped a hand over his face. His shoulders slumped. ‘I didn’t do it,’ he wheezed thickly. ‘You have got to believe me. I didn’t do it.’

Hodges smirked, clearly pleased at the change of tone of their charge. Gillard beckoned the detective outside with a finger, then closed the interview room behind him.

‘What’s the matter, boss?’ Hodges asked.

‘Michelle Davies backed his alibi, didn’t she?’

Hodges crinkled his face and held up one hand which he waggled ambivalently. ‘It was a bit lukewarm, to be honest. She couldn’t give me any details of what time she arrived or when she left. I think she was caught on the hop to be asked.’

‘You have got to be careful, Colin.’

‘Why? The brief never saw me, it ain’t on the tape. I think I nutmegged him good and proper.’

‘Well, before you go congratulating yourself, take a look at Waddington’s previous.’

‘It’s nothing. Single conviction for affray.’

‘There’s a lot more if you read the call­out log. Domestic violence, half a dozen police attendances in the last two years. Ms Davies would never press charges. The woman is separated from him now. And you’ve just given Waddington a massive excuse to go around and smack her one by hinting to him that she wouldn’t give him an alibi.’

Hodges face fell. ‘I didn’t realise that.’

‘Okay, now get the custody sergeant to take him back down the cells. I suppose you’ve just created another reason to oppose bail.’

As Hodges slouched away, resentment woven into his shoulders, Gillard’s phone pinged with the arrival of an email.

An email from the lab. First up was an apology for failing to get results to him by the close of business yesterday, followed by some bad news. The sweat sample of DNA on the murder weapon did not belong to Jason Waddington. Nor to anyone else on the national database.

After the interview Gillard returned to his office to get up to date with the paperwork. Before he had the chance to sit down, DC Carl Hoskins called to him. He was dressed in sweatshirt and jeans and nursing a coffee. He looked tired, even by his hangdog standards. ‘We made a couple of arrests last night at the Ashtead crime scene.’

Gillard glanced up only briefly at the officer. Hoskins’ tone of voice and expression, jocular rather than earnest, telegraphed that this was an anecdote rather than evidence. Nothing with a significant effect on the case. That would be a shame. With the extra resources Alison Rigby had allocated, Gillard had chosen teams of two plainclothes officers to keep an eye on the crime scene day and night, watching out for the proverbial assailant returning to it. He didn’t particularly expect it, but there was always a chance. From long experience Gillard knew it was always a slightly difficult judgement in any location where a surveillance car did not have access, and the officers would be seen. Two men walking in woodlands together at night looked pretty suspicious to many people, as indeed did a couple, especially if the woman was young. They could generate as many calls from the public as a real crime. The best insurance was a dog, a ready-made excuse for being in parkland.