But he could see what was bothering Kessen. The first twenty-four hours were the vital period after any murder. If you didn’t have a strong lead within that time, you were destined for a long drawn-out enquiry – and the odds were against bringing the case to a successful conclusion. This murder might be forty hours old already, according to the ME, and there wasn’t a single lead in sight.

But why didn’t someone miss Rose Shepherd? That was the question the DCI had asked earlier. And it was a good question.

‘You know, there’s absolutely no sign of an intruder being in the house,’ said Kessen. ‘Apart from this open window, which shows no traces of having been forced. No tool marks, no damage. Right, Wayne?’

Abbott had his phone to his ear. ‘And no fingerprints either,’ he said. ‘I just got an update. The only prints we found on the window are a match for the victim’s – and they were on the inside.’

‘And every other window in the house is locked down tight. Why wouldn’t this one be locked, too? Can anyone suggest an answer to that?’

‘Yes,’ said Hitchens, looking anxious. ‘Because someone used this window to get out of the house. I don’t know how he got in – I can only guess the victim let him in through the front door. But he must have gone out this way.’

‘We’re on the first floor. Did he clamber down the drainpipe?’

‘Probably.’ Hitchens looked out of the window. ‘Actually, there isn’t a drainpipe. Not within reach.’

‘A nice dense ivy, then? Russian vine?’

‘Nothing. It’s a blank wall . . .’ Hitchens hesitated. ‘He must have jumped.’

‘From this height?’

‘Er, yeah.’

‘In that case, Paul, I expect you’ll find the intruder’s prints on the window frame, perhaps some fibres from his clothes on the stone ledge. There’ll be some pretty deep footwear impressions in the ground down below, where he landed. Oh, and you’ll be looking for a suspect who ran away with two broken legs and a cracked spine.’

Hitchens sighed. ‘So what’s the alternative?’

Kessen joined him at the window. ‘There’s only one other possibility. That there never was an intruder in this house. The victim was shot from outside.’

Hitchens stared. ‘From the garden?’

‘No, look – the angle is completely wrong. The shots must have come from the field.’

‘But the window – why was it open?’

‘Wayne said there were no prints on the outside. What about the inside?’

‘Just the victim’s.’

‘So that’s pretty clear, isn’t it?’ said Kessen. ‘The victim opened the bedroom window herself. And someone waiting in the field shot her.’

‘Jesus,’ said Hitchens.

Kessen turned back and addressed the room in general. ‘Close off that road up there, seal the gateway, and get the SOCOs and the search teams into the field. That’s where our gunman was.’