Cooper thought of the expanse of Oxlow Moor, and the neighbouring areas. Old Moor, Bradwell Moor. That was a lot of ground to cover.

‘Did they check all the shafts?’ he said.

Hitchens held out his hands in a half-apologetic gesture. ‘Who even knows how many shafts exist out there? How can we say it was all?’

‘And why didn’t they get dogs in?’

‘Oh, the wrong kind of snow on the roads. The wrong kind of wheels on the snow. You know how it goes.’

‘Would you say the inquiry was ongoing?’ asked Fry.

‘Theoretically. It was never officially closed, but …’

‘But nobody has been putting any work into it, I suppose.’

‘Not for a long time. There have been no new leads. What do you expect?’

DCI Mackenzie stood up as a set of photographs was handed out. A head shot of Trisha Pearson, cropped from a group picture. She was dressed up, perhaps for a wedding, with her hair pulled tightly back. In the photo, it looked to be a deep chestnut red, but it could be misleading. He wouldn’t have said she was beautiful, but she was quite a striking woman, her face radiating health and confidence. She was laughing, and her eyes glittered as if life was just a bit of fun.

And then there was her husband, David Pearson. Clear blue eyes, and fair hair that was a bit longer than was fashionable these days. He reminded Cooper of a young Robert Redford from the 1970s. About the time of The Way We Were, perhaps.

‘As we all know, time is of the essence at the beginning of any investigation,’ said Mackenzie. ‘We have the golden hour, when there’s the best opportunity to make progress in an inquiry. Okay, we might push it further to the first twenty-four hours, or then the first forty-eight. But once you give up a crime scene, you start to lose things. Evidence becomes lost or tainted, and then it’s worthless. In this case, we lost control of the crime scene more than two years ago.’

He allowed a moment for that fact to sink in. Officers in the room shuffled their feet uncomfortably, as if they were already being told that this inquiry had failed.

‘So,’ said Mackenzie, ‘it looks as though our only hope of progress is to concentrate on the victims.’

‘Didn’t we do that last time?’ asked someone.

Mackenzie hesitated for a second. ‘Yes. But now we’re going to do it again.’

Cooper glanced across at Fry, but she wasn’t meeting anyone’s eye. Not on this side of the room, anyway. He knew she would be feeling in her element now. Forensics aside, it was the piecing together of the final minutes, hours and days of the victims that was the foundation of a modern murder investigation. Fry would already be working through in her mind the procedures to be followed, the files to be reopened, the potential leads to be analysed and followed up. Murder investigations these days were a world away from the TV stereotype of two detectives rolling up to the crime scene.

Many lessons had been learned from botched inquiries like the Stephen Lawrence fiasco. These days, the tactic was to flood a crime scene with officers to maximise the chance of uncovering vital early clues.

The original inquiry had tasked more than thirty officers to cover all the possible angles. Some had been assigned to the family, others were involved with the forensic examination. Uniformed officers had conducted house-to-house inquiries, while detectives spoke to witnesses. The Senior Investigating Officer had logged all his decisions – and after twenty-eight days, because there was no breakthrough, a review team had been called in to provide a fresh pair of eyes. Every decision had been recorded and was open to review.

It was known as victimology – the picture that a murder inquiry tried to build up of the relationship between the deceased, the location and the suspects who came into the picture.

As a result of the strategies and protocols put in place, the clear-up rates for murder in England and Wales were very high – more than ninety per cent of suspicious deaths were detected, meaning someone was either convicted, or charged and later cleared.

Yes, there were a few unsolved murders. Derbyshire Constabulary had ten of them on the books. No one wanted another one to add to the tally, and especially not two. The initial inquiry had failed to produce a result, but now they had another chance.

The trouble was, within a few days Divisional CID would get sidelined, and they’d all be back on burglaries and stolen postboxes.

‘If local officers could help us by reviewing the original inquiry into the disappearance of the Pearsons, going over the ground to see what might have been missed, it would be greatly appreciated,’ said Mackenze. ‘I think we could also use another physical search, but over an expanded area. I realise this will tie up some resources at an operational level.’

Branagh nodded her agreement, and Cooper knew his workload for the next few days had just been doubled.

‘Of course, our big piece of luck,’ continued Mackenzie, ‘is the find on Oxlow Moor. These are believed to be the Pearsons’ belongings.’

Now there was a stir of interest in the room. They were no longer going over old territory that had already proved fruitless. This was something new. Police officers were only human. They were motivated by the prospect of making genuine progress and achieving results. It was what gave them that frisson of excitement.

Mackenzie indicated large photos fixed to the whiteboard behind him.

‘So – first we have a couple of matching Levi’s anoraks in bright orange, with chambray linings. Not my style, but nice and visible in bad conditions, I’m told. As you can see, the larger of the two garments has staining on the left shoulder and left arm, here and here. Confirmed as human blood.’

The stains were clearly visible in the scenes-of-crime photos, dark against the orange fabric of the anorak, which had been laid out on a table under powerful lights. Some forensic expert would even now be trying to analyse the direction of the spatter, the force of the spray, calculating angles and the position of the wearer.

‘Then there’s a small Italian leather rucksack. This purple doesn’t seem to go with the anoraks, but what do I know? All three of these are items the Pearsons were seen with during their visit to Castleton on that last evening, and have been confirmed as their possessions. And even if we didn’t have those …’ The DCI gestured at two more photos. ‘This is David Pearson’s wallet, containing a little over two hundred and fifty pounds in cash, three credit cards, his own business cards and several membership cards – gym, AA, frequent flyer points and so on. Obviously this leaves us in no doubt. All of these items, ladies and gentlemen, were deliberately buried in peat on Oxlow Moor, about a mile from the cottage where the Pearsons were staying.’

Cooper studied the photographs carefully. The items might leave no doubt about identification, but they certainly left room for speculation about motive. If David and Trisha Pearson were attacked and killed, why weren’t they robbed too? In particular, why would anyone leave that amount of cash?

‘Fingerprints?’ someone was asking.

‘Working on it.’

That was a given. No expense spared, probably. After all this time, there would be an all-out effort to get forensic results. But it could take time.

‘Luckily,’ said Mackenzie, ‘a complete forensic sweep of the cottage was done at the time. No sign of a break-in, or of any violence taking place there. But after some work by the lab, they did manage to obtain enough DNA from tooth-brushes, used clothing, follicles on hairbrushes and so on to build DNA profiles for the victims. I mean, for David and Trisha Pearson, of course.’

‘If they are victims.’

‘Absolutely. Meanwhile,’ Mackenzie looked towards Fry, ‘we’ll also be concentrating on making some early progress on the fresh incident. Let’s see if we can confirm a connection between the two.’