But Hitchens was into the flow now that he’d made a decision, and he started counting off on the fingers of one hand.

‘Secondly, we need to interview anyone who was working at the firm eighteen months ago, at the time of Audrey Steele’s funeral. Any former employees who’ve left since then will also have to be traced. Background checks on them all, plus any known associates. We have to narrow down the list of names to those who had the opportunity to interfere with the body. A motive would be helpful, too. But God knows what that might be.’

The DI looked at Cooper. ‘How does that sound for starters, Ben?’

Cooper had been trying to make notes. ‘Great,’ he said. ‘And what about the family, sir?’

‘Audrey Steele’s family? That’s a bit delicate, isn’t it? But one of them might have noticed something, so they’ll all have to be interviewed.’ Hitchens stopped counting fingers and steepled them, as if praying. ‘Handle that yourself, Ben. You’ve already spoken to the mother, you said? I suppose she’s getting on a bit?’

‘Yes.’

‘Well, treat her with kid gloves and don’t upset her too much. See if you can find some other members of the family who might be easier to talk to. You know what I mean?’

Cooper nodded. ‘I know what you mean.’

‘Diane,’ said Cooper when they’d left the DI’s office, ‘I don’t think you’re doing yourself any favours with the DI, or with Mr Kessen either. You didn’t seem to give Dr Kane’s views any respect.’

Fry slapped her notebook down on her desk. ‘Have you ever killed anyone, Ben?’

‘No, of course not.’

‘Nor me,’ said Murfin from the next desk. ‘I’ve thought about it a few times, obviously.’

‘I didn’t ask you, Gavin.’

‘What’s your point?’ asked Cooper.

‘My point is, if none of us have ever killed anyone, how can we possibly know what it feels like?’

‘We can’t. Not really.’

‘And Dr Rosa Kane? Do you think she’s ever killed anybody?’

‘I’ll run a check on the PNC, if you like, and see how many murder convictions she has.’

‘Don’t be stupid, Ben. It was a hypothetical question.’

Murfin laughed. ‘Please dispose of your hypotheticals safely, in the interests of the staff.’

Fry glared at him, but he kept his head down. Cooper thought of the legend of the Gorgon, whose gaze could turn you to stone if you looked at her face. Gavin must have read that story. He rarely met Fry’s eye these days.

‘The point is,’ she repeated, ‘even the precious Rosa doesn’t know what it’s like to kill someone. Despite all her theories, she can’t actually tell us what goes on in a killer’s head, how he feels before and after the act. Let alone during.’