Another gap for my I told you so. I can’t take any longer sitting there next to him, being polite to each other under Breslin’s amused eye. I say, ‘Did you find a reason to think any of this has anything to do with our case?’

‘No.’

‘Good. Then let’s get this meeting done.’

I stand up. Even before I reach the front of the desk, the floaters have dropped their work and are sitting up straight, managing to be all attention without God forbid making eye contact with the rabid animal.

‘OK,’ I say, ‘good news. It’s looking pretty definite that Rory Fallon is our boy. He and the CCTV both say he’s been stalking Aislinn for at least a month. That’s how he spent the missing time before their date on Saturday night – or part of it, anyway: peeping in her windows.’

‘Little perv,’ Stanton says, grinning. ‘Better swab her walls for DNA.’

A quick edgy smatter of laughs. ‘Do it,’ I say. Rory’s leftovers might not prove murder, but they’ll up our chances at trial; juries hate a wanker. ‘He says he was hanging out in the laneway behind her patio, so get the techs to give that wall a good going-over – and try the wall under her kitchen window, too, just in case he got up the guts for a little close-range action.’

Stanton nods; Meehan puts it in the book of jobs. I say, ‘Our new working theory is that, when Rory arrived in Aislinn’s house, she somehow found out about the stalking. She told him to get out, and he lost the head.’

‘Rory hasn’t spilled the beans yet,’ Breslin says, ‘but he’s come close. We’re hoping tomorrow’s the day.’

‘Before we pull him back in,’ I say, ‘let’s find out just how much stalking he did, and what kind. I need two guys walking Rory’s picture around Stoneybatter to see if anyone recognises him from the last couple of months. He’s got the bookshop to run, so we’re mainly looking at evenings and Sundays. Try everywhere: houses, shops, pubs, offices where the workers might’ve crossed paths with him on their way out. Any community groups or bingo nights or sports clubs, track down the members.’ Kellegher lifts a finger. ‘Kellegher, you and Gaffney take that. And I want to know what Rory’s phone’s been doing over the last two months: when it pinged towers around Stoneybatter, whether it logged onto any wireless networks in the area. Stanton, while you’re making calls, make those.’

The case has changed. Before, we were dragnetting, sifting through what came up and hoping there was something good in there. Now we’re hunting. We’ve got the prey in our sights and we’re closing in, and everything we do is building towards the moment when we’ll have him pinned down for the kill shot.