Bernard Duncan Philips, AKA Roadkill, was slumped in one of them, DI Insch leaning against the sink opposite. Between them a small candelabrum flickered. Only two of its five sockets had any candles in them, and they were little more than stubs. No one said a word as Logan entered.

Insch's face was like stone, scowling down at the sagging figure. He must have been thinking the same thing as Logan: they'd had him last night and they'd let him go. And now they had another dead child on their hands.

I've sent the duty doctor home.' Logan's voice was swallowed by the gloom.

'What did he say?' asked Insch, not taking his eyes off Roadkill.

'It's probably a little girl. We don't know how old. She's been dead for a long time. Maybe years.'

Insch nodded and Logan knew he was feeling relieved. If the kid had been dead for years then it didn't matter that they'd let Roadkill go last night. No one had died because of that.

'Mr Philips here has declined to comment. Haven't you, Mr Philips? You won't tell me who she is, or when you killed her. Funny how we've now got two dead girls on our books, isn't it? Even funnier how we've got some sick bastard running round killing little boys and sticking things up their arses. Cutting off their dicks.'

Logan frowned. David Reid had turned up dead and mutilated in a ditch on the other side of the city. Roadkill liked to keep his dead things. He wouldn't leave a prize like that lying out in the open.

'You know,' said Logan, trying to play good cop. 'We could make this a lot easier for you, Bernard. You tell us what happened. In your own words, OK? I'm sure you didn't mean for all this to happen, did you?'

Roadkill slumped forward until his head rested on the scarred tabletop.

'Was it an accident, Bernard? Did it just happen?'

'They're taking them all away. All my beautiful dead things.'

Insch slammed his huge fist down on top of the table, making the candelabrum and Roadkill jump. Hot wax spattered onto the wood. Bernard Duncan Philips slowly sank back down to the tabletop, covering his head with his arms.

'You're going to jail. You hear that? You're going to Peterhead Prison, with all the other sick bastards. The paedophiles, rapists, murderers. You going to be someone's bitch up there? Going to find the love of your life in some hairy-arsed Weegie bastard? 'Cos if you don't start talking to us I'm going to make sure you get shacked up with the skankiest arse-raping bastard they've got up there!'

It was designed to get a response. But it failed. In the uneasy silence Logan could hear a quiet tune. Roadkill was humming something to himself. It sounded like 'Abide with me'.

The kitchen window filled with light and Logan cleared a hole in the grubby glass. The Identification Bureau van was struggling its way up the track. It stopped outside steading number two. There was another car behind it. Something sleek and expensive which was having trouble with the snow-covered drive. By the time it drew level with the farm buildings, the technicians had started humping their equipment from the warmth and safety of the van into the charnel house.

The car's driver clambered out into the snow. It was Isobel.

Logan sighed. 'That's IB and the pathologist.' He watched her turn her collar up and slither around to the boot of her car. She was wearing a long camel-coloured coat over her tan suit. She struggled out of her Italian leather boots and into a pair of wellies before clumping her way into the steading.

Thirty seconds later she was out in the snow again, bent double, breathing hard. Trying not to be sick. A grim smile spread itself over Logan's face. It wouldn't do to appear human in front of the lower ranks.

Insch pushed himself away from the sink and produced a pair of handcuffs. 'Come on, Philips. On your feet.'

Logan watched as the bedraggled figure was read his rights and the cuffs were snapped into place, hands behind his back. Then Insch dragged Roadkill out of the kitchen and off into the snow.

Alone in the house, Logan blew out the candles and followed.

This time Roadkill's 'appropriate adult' was a rundown man in his early fifties, thinning on top and sporting a ridiculous little moustache. Lloyd Turner: an ex-schoolteacher at Hazlehead Academy who'd recently lost his wife and wanted something to take his mind off being alone all the time. He sat at the table next to Bernard Duncan Philips, facing the combined scowls of Detective Inspector Insch and DS Logan McRae.

The small room smelled. Not just the usual, inexplicable whiff of cheesy feet, but the stale sweat and rotting animal odour that Roadkill exuded. The bruises Logan had seen last night had blossomed. Dark purple and green spread over the prisoner's face, disappearing into his matted beard. His hands fluttered on the tabletop, the skin dirty, the nails black. The only clean thing about him was the white paper boiler suit the Identification Bureau had given him when they'd taken his clothes away for forensic examination.

Logan and Insch had spent three hours getting exactly nowhere. The only thing they could get out of Roadkill was that someone was stealing all his precious dead things. They'd tried being nice; they'd tried being nasty. They'd tried getting the ex-teacher with the moustache to talk to him, to explain the seriousness of the situation. Nothing.

DI Insch rocked back in his seat, making the plastic creak. 'Right,' he said with a sigh. 'Let's try this again shall we?'

Everyone round the table grimaced, except for Roadkill. He just went on humming. Abide with bloody me. It was beginning to drive Logan mad.

The teacher put up his hand. 'I'm sorry, Inspector. I think it's quite clear Bernard is not in any fit state to be interrogated.' He cast a sideways glance at the smelly man sitting next to him. 'His mental state is a matter of record. He needs help, not incarceration.'

Insch slammed his chair forward. 'And the kiddies lying dead in the morgue need to be safe and sound at home, not killed by a twisted weirdo!' He crossed his arms, straining the seams on his shirt, making himself look even bigger. 'I want to know where Peter Lumley is, and how many other little kiddies he's killed.'

'Inspector, I understand that you're only doing your job, but Bernard isn't in any fit state to answer questions. Look at him!'

They did. His hands were like wounded birds, flapping away on top of the table. His gaze was far and distant. He wasn't even in the same room as them.

Logan glanced at the clock on the wall. Seven-twenty. Past the time when Roadkill started asking for his medicine yesterday. 'Sir,' he said to Insch, 'can I have a word with you outside?'

They walked to the coffee machine, passing an array of interested faces. The word was all round the station, on the radio, and probably the evening news. The Aberdeen Child-killer was behind bars. Now all they had to do was get him to talk.

'What's on your mind, Sergeant?' asked Insch, punching in the number for white coffee, extra sugar.

'We're going to get nothing out of Roadkill tonight, sir. He's schizophrenic. He needs to take his medication. Even if we got a confession out of him it'd get ripped to shreds in court. Mentally ill suspect, denied medication, confesses after a three-hour interrogation? What would you do?'

Insch blew across the top of his plastic cup of coffee and sipped experimentally at the liquid. When he spoke at last it was with the voice of a very tired man. 'You're right of course.' He sat the coffee down on the nearest table and hunted through his pockets for something sweet. In the end Logan had to offer him one of his extra strong mints.

'Thanks. I've been thinking the same thing for the last hour. Just didn't want to let it go. Just in case.' He sighed. 'Just in case Peter Lumley's still alive somewhere.'