Detective Cullen cleared his throat. ‘As you know, Peadar, we’ve arrested the Lee Pusher and we have her in custody. We’re preparing the book of evidence against her, and now that you’ve had some time to get over the shock of Roisin Carroll being drowned, we thought we’d ask you to think again about what you saw. Maybe there’s one or two extra details that didn’t come to mind when you first described what happened. Sometimes it’s details like that can help to make absolutely certain that an offender gets convicted.’

Peadar thought for a while, and then took a packet of Major cigarettes out of his sweater pocket and lit one. ‘I can see it now – Roisin pushing her stroller along the path by the river. Then this tall feller in the grey trackie running towards her. Well, I thought it was a feller at the time, because he looked like a feller. Tall, and skinny, like. And he ran faster and faster and crash! straight into her, and splosh! into the river she went, go-car and babby and all.

‘The feller ran off but I didn’t pay no mind to him after that because I was too busy jumping into the river meself and fishing out the babby.’

‘Can you describe him again, this feller?’ asked Detective Walsh. ‘Let’s call him a feller for now, because that’s what you thought at the time. You’ve already told us that he was tall, and thin, wearing a light grey tracksuit with a hood. Do you remember if he was wearing gloves? And what kind of shoes he had on? Was there anything unusual about the way he ran? I mean, did he run like a girl, with his arms waving?’

Peadar took a long drag at his cigarette and then blew smoke out of the side of his mouth. ‘I can’t think of nothing more, like. Gloves? I couldn’t tell you. As for the way he was running, it was like sprinting, you know, with his arms chopping up and down on either side of him. Not like girls run, not at all, no.’

Dr Power was sitting closest to Peadar. Now she leaned towards him and said, ‘Could you do me a favour and lift one finger for me? No – not with your cigarette hand, your other hand.’

Peadar did as he was told and lifted his left index finger. He had allowed the fingernail to grow so long that it curved over, and it had a black semi-circle of dirt underneath it. ‘What’s this for, then?’

‘It’s a way to help you remember,’ said Dr Power. ‘Stare at the tip of your finger, don’t take your eyes off it, and blink as little as you can. Try and think about nothing else at all. Not the pusher, not Roisin going into the river – only the tip of your finger.’