Donal glanced left and right at the two prison guards sitting either side of him. Their faces were impassive but Katie was quite sure that they had been listening with suppressed relish to Donal telling her all about Billy, and that they would be repeating all the gory details in the staff canteen as soon as they had the chance.

‘Three years ago, the first treatment,’ Donal told her. ‘Only the pills at first. The what-do-ye-call-thems. The hormones.’

‘Did something happen in her life to make her decide to start transitioning? I mean, any stressful event?’

‘I can’t tell you that.’

‘Why not, Donal? It won’t be going any further.’

Donal didn’t answer, but looked down at the table again.

‘But I’m guessing that something did happen, even if you don’t feel that you can tell me about it?’

Still Donal said nothing.

After a while, Katie said, very gently, ‘Can you think of any reason why somebody would want to kill Billy? Maybe they were aiming for Thomas O’Flynn and they missed, but what if they weren’t? What if it was Billy they were after? Can you think of any motive they might have had?’

Donal remained silent.

Katie and Robert and Detective Caffrey waited patiently, but after three or four minutes of silence it was clear that Donal had said all that he had needed to say, and that he had no intention of answering any more questions.

‘Right,’ said Katie. ‘Thank you for what you’ve told us, Donal. It would have been pure helpful if you could have told us a little more, do you know, but Billy was your brother, and we respect your grieving for him. If you have second thoughts about it, you have only to ask the prison staff here and they’ll arrange for us to talk some more, either in person or on the phone.’

She stood up, giving him a few more seconds to change his mind, but he didn’t speak or raise his eyes, and so she turned around and left the interview room, followed by Robert and Detective Caffrey. They said goodbye to the governor and walked out into the chilly afternoon.

‘That last question was critical,’ she said, as they climbed back into their car.

‘He didn’t answer it,’ said Detective Caffrey, from the back seat.

‘That was why it was critical. He didn’t answer it because he didn’t want the guards to hear what the answer was.’

‘So?’

‘He didn’t want the guards to hear what the answer was because it’s connected somehow with the reason why he shot Michael Riordan and his family. I reckon that it could well have been a giveaway that Thomas O’Flynn contracted him to do it.’

‘That’s a stretch, isn’t it, ma’am?’ asked Robert.