Having left him to stew for an hour or two before interviewing him the first time, Caroline was tickled when Walsh presumed he was then free to go. She’d taken great delight in disabusing him of that notion, telling him they’d need to interview him again later in the day, then escorting him back to his cell.

Although the clock wasn’t strictly on their side, and they only had twenty-four hours from booking him in until they had to either charge or release him, Caroline was a fan of using it to her advantage. Winding the clock down meant Walsh would either get increasingly annoyed and frustrated or — perhaps even better — would gain a false sense of confidence, presuming the police were struggling. Knowing Walsh’s arrogant personality, Caroline was willing to put money on the latter.

The team had been busy collating further evidence, looking for proof that he’d sent Roger Clifton the death threat by email, and were attempting to make forensic links. Walsh’d had his DNA taken on being booked into custody, and Caroline had been frantically awaiting results of a link. She knew it was unlikely they’d come back in time, but waiting had the added benefit of leaving him to stew in his cell for a little while longer.

By the time Walsh’s second interview rolled around, it was approaching midnight. Chief Superintendent Derek Arnold had hung around until just past ten, keen to keep abreast of the situation. After all, murder didn’t often visit Rutland. But even he had given in to the call of home, leaving only Caroline, Dexter, Sara and Aidan in the office.

Caroline and Dexter sat down in the interview room, trying to look more awake and alert than Walsh, who’d had nothing to do but sleep in his cell for the past few hours, and hoped their fixes of black coffee and Haribo Tangfastics would keep them going long enough. With Walsh’s custody clock running out late the next morning, they could be in for a long ride yet.

‘So, Patrick. You told us you were at home on the night Roger Clifton was murdered, is that right?’

‘Yes,’ Walsh said, a little less certain than he had sounded earlier.

‘Okay. We’ve got mobile phone cell site data which shows the approximate area your phone was in at the time. Do you want to change your answer based on that?’

At this point, most suspects tended to try to wriggle out of it by claiming they’d lost their phone or had left it somewhere accidentally. Proof of their mobile phone’s location wasn’t the same as proof of their location.

Walsh swallowed and sat back in his chair, folding his arms. He glanced off to the side, as if trying to concoct a story in his head.

‘No comment.’