‘I’ll grab it,’ Nadia said, and snapped on a pair of gloves. She picked it up and read it. Wynne put her own gloves on and, when Nadia was finished, held out a hand.

She scanned the letter.

‘Who else has handled it?’ she said.

‘Only me and Tom.’

‘Tom?’ Wynne said.

‘My husband. He’s upstairs putting our daughter down.’

‘No one else?’

‘The post office, I suppose.’

‘They would only have touched the envelope,’ Nadia said. ‘We’ll need to take your and Tom’s fingerprints to eliminate them from the letter.’

‘And then you’ll be able to get the prints of whoever wrote it?’ Alice asked.

‘If they’re there,’ Wynne said. ‘I’d be surprised if they were so careless. But we’ll look. Talk me through what happened, if you would, Ms Sark.’

‘Not much,’ Alice said. ‘The post arrived and I saw the envelope. It didn’t look like junk mail, so I opened it.’

‘So it came with the post?’ Nadia said. ‘Not hand delivered?’

‘Yes,’ Alice said. She pointed to the envelope. ‘It’s been franked, so it went through the postal service.’

Nadia nodded. ‘The article it refers to – that was published on Sunday, if I remember correctly?’

‘Yes,’ Alice said.

‘So the letter was posted Monday and arrived today,’ Nadia said.

‘Or Sunday,’ Wynne said. ‘And picked up Monday.’

‘And it’s definitely the killer,’ Alice said. ‘There’s the comment about the keys. Where were they?’

Nadia glanced at Wynne. ‘In her mouth,’ she said. ‘They were stuffed in her mouth.’

‘So it’s the killer, all right,’ Wynne said. ‘No one else could have known that.’

There were footsteps on the stairs and the door opened.

‘Hi Nadia,’ Tom said, and then turned to DI Wynne and introduced himself. ‘I’m Tom Sark.’

‘Detective Inspector Jane Wynne. Pleased to meet you. You were out when this arrived?’

‘I was at work. Alice called me to come home.’

Wynne took an evidence bag from her pocket and slid the letter inside. ‘Do you mind if I take this?’

It wasn’t really a question. Alice shrugged.

‘Why do you think he wrote to Alice?’ Tom said. ‘Why pick her?’

‘Because she called him the Crucifix Killer,’ Wynne said. ‘So the killer – we can’t assume it’s a man yet – knows she’s in touch with us. She was the one who broke the story.’

‘And now this psychopath has her in his sights?’ Tom’s lips were white, pressed together in fury.

‘I don’t think she is in their sights,’ Wynne said.

‘You don’t think?’ Tom said. ‘What do you think?’

‘I think this is a way to open a channel of communication. It can happen in these cases. Serial killers sometimes want to be close to the investigation. It’s a game to them.’

‘That’s wonderful. But now she’s – we’re – in danger,’ Tom said.