Maeve Kerrigan. Jane Casey

God’s sake.’

      ‘I know.’

      ‘I’m talking about this.’ He waved the pasty at me. ‘I can’t get it open.’

      I picked up a pair of scissors from my desk and held them out to him. He stabbed the packaging from a height and an off-putting smell wafted across my desk. I’d schooled myself to cope with seeing repulsive things and smelling the worst kinds of decay, but the things Derwent volunteered to eat were in a class of their own.

      ‘Problem solving,’ he said, preparing to bite into the pastry. ‘It’s what you’re good at. When you’re not making problems for yourself, obviously.’

      ‘How am I making problems?’

      ‘You’ve got an easy one. A full confession. Yeah, it’s heart-breaking that she went to court and couldn’t get rid of him, but that happens.’

      ‘But Sheila Gleeson’s statement isn’t complete or accurate. It’s a matter of public record that he beat her. Why wouldn’t she mention that when she talked to me? She should have wanted to explain why she did it, but all she wanted to do was confess. She told me she’d done it before I got the tape machine running.’

      ‘No point in trying to hide it, was there?’

      ‘She didn’t try, though.’ I swivelled from side to side on my chair, troubled. ‘She wanted to be caught and she wanted to avoid talking about the real reason it happened.’

      ‘Murder is murder, even for the best of reasons. Some people can’t live with themselves afterwards. You’ve met enough killers to know I’m right.’