“I couldn’t have left it in place. I’ll talk to forensics, explain the scene couldn’t be secured. The rest of the forensics team are digging for bodies in the old orphanage gardens. The ground radar detected five likely burial sites all next to each other.” He passed over a photograph of the plaque at the bottom of the young oak. “This oak tree had been planted on top of the bodies, either using the planting as cover for exhuming bones, or as a memorial at the grave site.”

“Exhuming bones, sir?” Frankie’s puzzlement reminded him he hadn’t updated her properly.

“Sorry, Frankie, there’s a lot on my mind. I had the head of Inverness forensics on the phone earlier this afternoon. The bones that they told us were animal bones were human. Children’s bones,” he added.

“The missing children?”

“Looks very much like it. It will take weeks to track down any living relatives, if they exist, before we can genetically match the DNA to each name.”

“So, the single bone in the laird’s lock?”

“Finger. Metacarpal. From a child’s second or third finger, they think.”

“That lettering, it’s the same as the lettering on the hourglass.” Frankie had spotted what he’d seen.

“Then there’s this. It’s on the wooden stock of the gun Brian was sent through the post.” He passed over another photograph, the lettering indistinct through the plastic covering but still clear enough to tell it was the same calligraphy.

“Same killer.”

Corstorphine put his hands to his temples, trying to alleviate the headache that had been growing over the day. “Yes. It certainly looks that way. They must have known Brian would commit suicide. Whoever we’re looking for must be in the town, Frankie. They know too much about each of the victims, their history, their habits. They can even predict how their victims will react. More to the point, they knew what went on at that orphanage and now they’re having their revenge.”

The radio interrupted him. It was PC Lamb. “They’ve found two bodies so far, sir. Both young children. Over.”

“How long do they need to complete the investigation, Lamb? Over.”

The radio remained silent for a minute until a burst of static announced Lamb’s response. “Going to take all night they reckon, sir. Do you want us to stay put? Over.”

Corstorphine swore under his breath. Of course, they’d take days over such a dig. Every scrap of soil would have to be examined for evidence and the remains dealt with respectfully – or as respectfully as could be managed.

“No. I’ve asked them to arrange for reinforcements from Inverness to man the site. They should be there within the hour. Both of you head back to the shop when they arrive. Call me on the radio if I’m not here.”

“Sir.”