While this was going on, McNab simply watched. To his mind, what Mrs Jackson seemed most annoyed about was the fact that they’d found Mary McIntyre’s body, whereas she would have preferred that they hadn’t.

‘It was over and done with years ago,’ she was saying with a shake of her head.

‘Not for Mary’s family,’ McNab said. ‘Nor for her pal Karen.’

At the mention of Karen’s name, Eleanor pursed her lips. ‘Karen grew up and got married. She went on with her life, put it behind her. Like we all had to do.’ She paused. ‘Besides, we gave our statements to the detective when it happened.’

‘Back then it was a missing person enquiry,’ McNab said. ‘Now it’s a murder investigation.’ He nodded at Janice to begin.

Janice set up the recording, while Mrs Jackson fiddled with the clasp on her handbag, not looking at them.

‘What we want you to do is speak freely, Mrs Jackson. Answer the questions with as much detail as you remember. Is that okay?’

The woman gave a brisk nod, as though resigning herself to just getting on with it.

‘Right,’ Janice said. ‘Can you please tell us where you were when you first heard that Mary McIntyre had disappeared?’

The frown between her eyes deepened, and a wave of distaste twisted her mouth.

‘Why on earth does that matter?’ she said.

‘Just answer the question,’ McNab told her.

She threw McNab a disapproving look, before saying, ‘It was when I came home from work at Boots, the chemist.’ She drew herself up in the chair. ‘I was sixteen. It was my first job.’

‘What time was that?’ Janice asked.

‘The shop shut at six, so it would be around half six by the time I walked back. The police were out looking for her, plus most of the street.’

‘Where was Karen?’

‘In her room.’

‘Did you speak to her?’

‘I stayed with Mum. Dad was out with the search party, and she was upset.’

‘What about Karen?’ McNab said.

She shrugged. ‘She never said anything. She was never a talker, except when her pal Mary was about.’

‘Was she upset, crying, in shock?’ Janice tried.

‘She was silent, that’s all I remember.’

‘We’ve put out an appeal for everyone who lived nearby at the time to get in touch, in particular Karen. We’ve had no response from her. Have you any idea how we might contact your sister?’

She looked annoyed by the question. ‘I told the other police officers when they came round. We don’t keep in touch. I haven’t heard from Karen in years, and I don’t know where she lives now.’

‘So when was the last time you saw or heard from Karen?’

‘Mum’s funeral. She came to that,’ she said through pursed lips, as though it had been a crime.

They waited for her to continue. Eventually she did.

‘Look. Mary McIntyre’s disappearance destroyed every family on that street. It was like a poison, eating us all up. Everyone suspecting everyone else. It was evil. My father moved us away because my mum couldn’t cope with being there.’