‘It was the number I recognised. That’s why I didn’t connect the two.’ She felt shame rise to her cheeks – how could she not recall a victim but remember their telephone number? When had that happened? ‘I was called in to do telephone analysis on this domestic violence case. They needed phone evidence as he’d harassed the hell out of her using his mobile.’

Carla remembered the rows of numbers – the highlighted ones indicating O’Brian had called Gloria – and how she’d been shocked at just how many there were.

‘But that was all it was to me. Numbers. And now he’s killed a child.’

Bremer didn’t speak for a second or two, but when he did he spoke quietly and deliberately. ‘If we held every case in our head we’d go insane. If we didn’t let go of victims, or perpetrators, after each case was closed, then how could we function? I’d give us each two years, and that’s being generous. We deal with as much shit in a week as most people deal with in their whole lives. You save lives with numbers, so if that means you remember them above the victim, then I for one am glad of that.’

Carla didn’t know how to reply. Bremer put a hand on hers.

‘You’ve got the number. Now find out if it means we can catch him. OK?’

And in those few words he managed to refocus her. She had the number. ‘OK. I’ll need half an hour.’

Bremer smiled. ‘Good. See you back here in thirty.’

Carla picked up the phone.

‘Telephone Unit.’

‘Carla Brown. I’ve got a murder and need some telephones checking.’

‘Go ahead.’

Carla read out the phone numbers she’d got for Connor and Gloria. ‘Oh, and check out his girlfriend’s while you’re there.’ She gave Kelly-Anne’s number on the off chance Connor had contacted her and the woman knew more than she was letting on. ‘Incoming and outgoing calls, please.’

‘Got it. What about the victim’s phone – want me to run that too?’

‘Too young.’

‘Shit.’

‘Yeah, three months old.’

‘Jesus.’

They paused to acknowledge the magnitude of the crime, but in truth they’d both been there before.

And there Gloria was again. Seated in the corridor, hands clasped between her knees, her son playing with a fire engine at her feet. Shit. She’d forgotten the woman had a son: small, brown-haired, always alert, looking to his mum for direction. What had he been then, two?

‘Is it a threat to life?’

Carla sighed. ‘He’s a danger to his current and ex-girlfriend,’ she said. ‘But I wouldn’t go as far as a threat to life.’

‘Got it. I’ll do it as soon as I can, but—’

‘Yeah, I know, it’s lower on the list. Just as soon as you can,’ she added.