I say, ‘So after the victim went down, either she lifted her head and then dropped it again, or else the killer did.’

‘Mmm,’ Cooper says. Steve is scribbling something in his notebook. ‘Either is possible. The killer could certainly have lifted her head to check for signs of life, or she could have attempted to get up but been unable to do more than raise her head. I would expect the initial injury to cause unconsciousness – there was some intraparenchymal bleeding, which generally has immediate neurological consequences – but it is plausible that she briefly regained consciousness before death.’

Steve passes me his notebook. Steve is about the only cop I know who has legible writing – nice writing, full of definite, old-fashioned loops and dashes; I think he practises in his spare time. The page says, Or: first a push – then the punch when she’s down?

I ask, ‘Could the injuries have come the other way round? The killer initially pushed our victim, rather than punching her; she went over backwards, hit her head on the fireplace, but not hard. Then when she was down and stunned, he went after her and punched her in the face?’

‘Ah,’ Cooper says, enjoying that. ‘Ah-ha. Interesting. And possible; certainly possible. Impressive, Detective Conway.’

‘That’s why they pay me the big bucks,’ I say. Steve mouths Hey! and points at his chest. I turn up my palm and grin at him: Nothing I can do, man, hate that.

‘Hmm,’ Cooper says, and I hear pages flicking. ‘In light of this new theory, I must revise my estimate of the killer’s strength. If the punch occurred when the victim’s head was already lying on the stone surround – rather than when she was free-standing, so to speak – it would have required considerably less force to inflict these injuries. Some strength would still be needed, but any healthy adult of normal muscular development could have done it.’

I’m giving Steve the eyebrows right back: that does sound like Rory Fallon. ‘Sorry to make you rewrite your report,’ I say. Cooper handwrites; none of us have the nads to invite him into the twenty-first century, so we get floaters to type up his reports.

‘I would forgive worse sins for the pleasure of hearing an alternative theory that fits the facts so neatly,’ Cooper says. ‘The rewritten report will be with you as soon as possible. I wish you the best of luck in finding hard evidence,’ and he hangs up.

Me and Steve look at each other.

‘That’s not manslaughter,’ he says.

‘Nope. Not if that’s how it went down.’ People get knocked down all the time, get up and hit back; no one expects that to kill. But if you punch someone in the face while the back of her head is up against a sharp stone edge, it takes some cojones to claim you thought she’d get up and walk away.