‘I’d say the trail had gone cold if there had been any trail in the first place. No bloodstains on the stairwell or the handle of the main door. Knife had probably been pocketed, meaning bloodied clothing if nothing else. Communal bins have been checked.’

‘Worth a dive team heading to the docks?’ Gamble enquired.

‘You volunteering, George?’ Trask asked back, raising a much-needed smile from the room.

‘Be honest, ma’am, you just want to see me in my parrot-smugglers.’

‘They’re called budgie-smugglers, George,’ Leighton corrected him.

‘I know what I’m talking about.’ Gamble seemed pleased someone had taken the bait, and the smiles around the room became quiet groans. Trask didn’t look put out by the moment of levity – it was sometimes needed, especially if a team was to feel like a team.

‘On a more serious note, though,’ she added, ‘Siobhan and Malcolm think they’ve got our 999 caller.’ She indicated for Clarke to take over. Fox insisted on joining her when she stepped forward, the two of them ending up flanking Trask.

‘Gaby Mackenzie,’ Clarke began, ‘short for Gabrielle. Daughter of the owners of the lettings agency. She met a special adviser at a party in Leith, knew there was an empty company flat nearby so took him there.’

‘We think,’ Fox butted in, ‘she noticed the door to the murder flat was open, knew it was owned by her father, so took a look. When she saw what was inside, she grabbed the spad’s phone and called it in. Then she ran, taking his phone with her.’

‘We got a description from the spad,’ Clarke took over, ‘and though fairly vague, it’s a match for Gaby Mackenzie, who has been known to visit the tenement on occasion.’

‘She’s been summoned?’ Trask checked.

‘Should be here any minute,’ Clarke confirmed with a glance at her phone.

‘Progress of a sort,’ Trask said, ‘which is of course to be welcomed. But let’s not lose sight of everything else. We’ve got a police officer suspended from duty, charged with domestic abuse; he worked at Tynecastle and was about to tell a few tales out of school; he was a frequent drug user. Plenty avenues to follow, and hopefully not too many dead ends.’

‘We’re bringing in his fellow officers?’ Gamble checked.

‘We are,’ Trask confirmed.

‘All of them?’

‘All of them. Phones and computers checked – anyone who refuses gets prioritised as a potential suspect. We need to know who he was in touch with, any online communities he was part of. But we can’t just depend on his phone and computer for help. I know it won’t be easy to convince his friends and colleagues to hand over evidence of their calls and texts to him, but we still need to try. He was active on Facebook, Twitter and Instagram, but I wouldn’t mind knowing about any other use of social media.’