Hitchens cocked an eye towards him. ‘Anything you want to contribute at this stage, DC Cooper?’

He straightened up, trying not to notice all the eyes suddenly turned towards him.

‘If we’re looking at the possibility of a professional hit, I can tell you that snipers are trained to pick up their brass,’ he said. ‘That would explain why there are no casings. They’re also told not to leave other clues to their identity or their shooting location. A trained person reconnoitres the site and selects a place that gives him cover and an escape route. Then he takes his shot. But normally only one – the sniper’s motto is “one shot, one kill”.’

‘But this suspect took three shots.’

‘To me, that doesn’t sound like a real professional.’ ‘There was no sign of any casings in the field, so we presume our suspect stayed long enough to pick them up.’

‘Well . . .’ began Cooper.

‘Yes?’

‘At night, in a ploughed field, that would be quite tricky. You’d be lucky to find one, let alone all three.’

‘True,’ agreed Hitchens, looking at him with interest.

Cooper leaned back for a moment and pictured the scene. He imagined himself sitting at the wheel of a car at night, in a ploughed field, with the driver’s window open and three bullet casings lying on the ground somewhere outside the vehicle.

‘Not just tricky,’ he said. ‘It would mean the suspect getting out of the car and leaving his footprints in the soil. He would pick up earth on his shoes and trail it back into the vehicle. That’s three possibilities for trace evidence. But the scenario doesn’t fit, does it? It’s not consistent with the planning before and after the hit.’

‘And there were no footprints in the area where the shots were fired from, just tyre marks,’ pointed out Hitchens. ‘Maybe the casings fell close enough to the car that the gunman was able to lean out of the door and pick them up without leaving the vehicle.’

‘No, that won’t work. It was a high-powered rifle. The casings would have been ejected at speed.’

‘What, then?’

‘The only possibility I can see is that the casings must have been ejected inside the car.’

‘Is that possible? If he was firing a rifle from the driver’s seat?’

‘The car was facing northwards, up the field, wasn’t it? With the back fence of Bain House on the driver’s side?’

‘Yes.’

‘Then, no,’ said Cooper. ‘I don’t think it is possible. Whoever fired the rifle would have had to be in the passenger seat.’

There was a sudden buzz of interest. Cooper felt himself flushing – not with embarrassment, but excitement. He was sure he’d got this right. He could see it so clearly.

‘We’ll have to get this checked out properly,’ said Hitchens.