‘It was just as much my fault.’ The husband was determined to shoulder his share of responsibility. ‘I told him he had to pay his way now. We spoilt him when he was a boy, Sergeant. Our only son. Money no object. We gave him whatever he wanted. It came hard to him when that had to stop. Especially when he hooked up with all those rich southern kids in uni. I could tell he blamed me. He was bored silly in that job in the health club. Sometimes I could see him looking at me and I knew he thought I’d let him down.’

‘Is that why he started stealing?’ Joe knew all about that now. Vera had called him as soon as she’d left Lisa’s house. Find out from the parents what was going on there. Did Jenny Lister catch him thieving? ‘Because it wasn’t for the cash, was it? He’d have hardly made enough to buy a couple of pints in the uni bar. Was it because he was bored?’

Now both parents turned on Ashworth. Fierce looks. A stony silence broken by Derek. ‘You can’t accuse the boy. He’s dead. He can’t fight back.’

‘If you want us to find his killer,’ Ashworth said, ‘you have to help me here. We have a witness who saw him take money from the staffroom. Did he know he’d been seen?’

Another silence.

‘You don’t seem surprised,’ Joe said gently. ‘If it’s not relevant, his stealing will never be made public. The witness won’t talk. But you must tell me what you know.’

‘I didn’t know,’ Karen said.

‘But you guessed? Suspected?’

‘He’d been moaning about being skint one morning and then suddenly there was a ten-pound note in his pocket and he was buying coffee in the hotel lounge before his shift started. I wondered.’

‘That must have been terrible,’ Joe said. He imagined finding out that one of his own kids was a thief. ‘It must have eaten away at you. Did you discuss it with anyone at work?’

‘No!’ The thought appalled her. ‘He was going to be a lawyer. If anyone found out, he could ruin the whole of his life for the sake of a cup of coffee. A few more days and he’d be in Bristol and we could forget the whole thing.’

It occurred to Joe that this woman had spent her life protecting her son and had created a monster. Would she kill to protect him? Perhaps, but there was no possibility that she would have stood behind him in the garden and strangled the boy, who had been, he saw now, her passion.

‘Did you discuss it with Danny?’