Perfect Prey. Helen Fields

of it like a bullet, with micro detail that links it to having been fired from a specific gun,’ Ailsa said. ‘All blades leave different impressions if you look closely enough. Find me that blade and I’ll be able to tell you if it’s a good match for this incision.’

      ‘That helps with evidence at trial but it doesn’t identify the attacker,’ Callanach said. ‘So who am I looking for?’

      ‘Someone who knows their way around the human body, who is not the least bit squeamish. A person who enjoys the spectacle. But that’s not why I got you here. Look at this.’ She tapped a key and another image popped up. The same smooth line ran down one side, a microscopically jagged edge along the other.

      ‘I see the same markings.’ Callanach walked back to look down at Michael Swan’s face. ‘Which section of the wound is that picture from?’

      ‘None of it,’ Ailsa replied. ‘You’ll be needing to look at Sim Thorburn’s injuries for that.’

      Callanach stood still and let it sink in.

      ‘But that was a double blade. It can’t have been the same weapon as was used on Thorburn,’ he said.

      ‘Not the same weapon, but possibly scalpel blades manufactured in a single batch, all with the same minuscule flaw. The first two blades were used to home-craft the weapon that killed Thorburn. The next one became part of a more traditional knife. Without seeing the blades themselves I couldn’t swear to this in court, but between us, I’d say whoever killed one, killed the other. And there’s more than that. Come here,’ she said, beckoning Callanach over to Michael Swan’s body. ‘The scalpel’s point of entry is at the left lower jawbone and the victim needs to be lying down for this to work. The only way to get such a clean cut would have been for the killer to have been sat at the crown of the head, like so.’ Ailsa positioned herself behind the top of Swan’s head and held her pen as if it were the knife. ‘Starting at the left jaw and pulling backwards means the killer was using their left hand. It didn’t occur to me with Thorburn until I was doing this autopsy today, but the draw of the blade on Sim was from his right to his left. The video footage you have shows the perpetrator passing in that direction. I think the killer chose the direction of walking specifically to allow them to use their left hand.’

      ‘Anything else?’ Callanach asked. His mind was full of possibilities. The links between Thorburn and Swan. The description of the killer from the festival who was short and light, hardly a good candidate for hauling a grown man up to a ceiling beam. A growing sense that this was a beginning and that there was worse to come. ‘What could be worse than this?’ he asked aloud.

      ‘If you want the worst,’ Ailsa answered, assuming the question was for her, ‘then you’d best have it all at once. It was the loss of blood that caused heart and brain function to cease for Michael Swan, just as for Sim Thorburn. Swan was alive when he was skinned. And he took a while to die. It was torture of a degree that I find difficult to describe adequately. I see no evidence that he was drugged to make him compliant whilst the procedure was undertaken, although the toxicology screen will take a couple more days. Who’ll be taking DCI Begbie’s place while he’s on sick leave?’

      ‘We’re answering directly to Superintendent Overbeck on the current open murder cases,’ Callanach said. ‘She’ll need to be copied in on the autopsy report.’

      ‘She’ll have it tomorrow. You’ll be needing to rest your back now. No point aggravating it any further.’

      ‘It’s potentially a serial killer getting started then, Ailsa, that’s what you think?’ he asked quietly.

      ‘It’s a possibility we cannot afford to ignore. You and I have seen enough to recognise the signs. When people enjoy killing to this degree, there’s very little that stops them until they’re captured or dead.’

      ‘Ailsa, about the leaking of the autopsy report on Ava’s investigation into Helen Lott’s death …’ Callanach began.

      ‘I know what you’re going to say and I agree it would be disastrous for that to happen here. But it was no one in my department, Luc. If you find that I’m wrong, I’ll take full responsibility, but my staff respect what we do here, no matter how long the hours they work and how difficult the circumstances. No one does this job for the pay or the glory, and those who don’t like it leave pretty damned fast. Everyone my end has been interviewed about the leak and our procedures have been security-checked for weaknesses. We’re clean.’

      ‘I can’t believe it’s anyone at the station,’ Callanach said. ‘No one could have accessed it who didn’t have proper security clearance. I don’t see what there was to gain.’

      ‘Don’t get too distracted with it now,’ Ailsa cautioned. ‘I’d say you have more than enough on your plate. I believe you have two dead by the same hand.’

      ‘Even so,’ he said. ‘Would you keep this offline? Do it the old-fashioned way. No emailing of reports, typed-up paper versions only. I can’t take the risk of this getting into the public domain.’

      ‘If you feel that strongly about it, then of course,’ Ailsa said. ‘Now off you go and protect the good people of this city. They’re having a very bad month indeed.’

       Chapter Eleven

      ‘Tripp!’ Callanach yelled as he limped down the corridor towards the briefing room. He stopped. Tripp wasn’t there, of course. Borrowed to become one of DCI Edgar’s hacker hounds, Tripp was no use to him now. He found DC Salter and waved at her to come to his office once she’d finished her phone call. He bundled up his coat to act as a cushion and sat down very slowly indeed. His fractured coccyx was producing a stabbing pain that made concentration difficult.

      ‘What’s the news?’ Salter asked as she came through the door.

      ‘All bad. There must be some CCTV footage between the McDonald Road Library and Regent Gardens where Michael Swan’s belongings were found. Find something. I know it was probably dark, but I need you to compare it with the footage from The Meadows killing.’

      ‘But that was a totally different thing, sir. Surely you don’t …’ Salter stopped. Callanach met her stare with a direct look. ‘Oh shit. All right, then. I’ll get on it.’ She looked pained. Callanach felt the same way.

      ‘Not a word to anyone else yet, Salter. Get started. I’m calling a briefing for this afternoon but this cannot get out.’

      As Salter left his office, DCI Edgar entered.

      ‘Sir,’ Salter greeted him, with a polite nod of her head.

      ‘Fetch me a cup of tea if you’re not busy, Constable. Strong. No sugar,’ the Detective Chief Inspector added.

      Callanach gritted his teeth and stood up, feeling the fractured halves of his coccyx grate as he moved. He fought the desire to notify Edgar that DC Salter was, in fact, very busy indeed and that the addition of the word please would have made such a request more palatable.

      ‘Can I help you, sir?’ Callanach muttered, reaching in his pocket for another dose of painkillers.

      ‘Came to see you about DC Tripp. He’s not got the training my squad have, but all the same he’s a worker. Thank you for the temporary transfer.’

      Callanach wondered what he was supposed to say, and more importantly, when he’d be able to sit back down.

      ‘How did your raid go, sir? I gather you had a firm lead on your hacker,’ Callanach said when it was clear Edgar was in no mood to disappear.

      ‘It was a useful exercise. Cutting off his exits, reducing his options. He knows now that we’ve discovered one of his bases. He’ll find it increasingly hard to get into his system without us realising he’s online and picking up a trace.’ Edgar picked a non-existent piece of fluff off his sleeve.