‘I’d say between nine in the evening and four in the morning. Can’t do better than that, sorry. Stomach contents are no help because there are none. The small intestine’s also empty, so it looks like it was at least twelve hours between her last meal and the time of death.’

‘No question that he kept her before he killed her, then?’

‘Looks that way. And that he beat her regularly while he had her.’

‘That fits with our thinking,’ Fielding snapped. ‘Thank you, Doctor. I appreciate your help. When will we have your full report?’

‘My secretary will email it to you as soon as she’s finished the transcript. Good luck with your investigation. This is a bad one, Inspector.’ And he closed the connection.

‘Nothing there we couldn’t have predicted,’ Fielding said, her tone suggesting that Grisha had failed them.

‘Apart from the possible taser wounds.’

‘Well, he had to have some way of subduing her and that’s one of the more straightforward methods.’ Fielding wasn’t giving any ground.

‘Three separate times, though. And only one of them in a place where the taser would get you from behind. That’s interesting. And what Grisha said? It does support our theory that she never went to Poland.’

Fielding grunted and started typing texts into her phone. There was none of the batting around of ideas and possibilities that Paula had grown used to in the MIT. All of her colleagues had thrived on speculation, trying out theories and testing them against the evidence. Whatever was going on in Fielding’s head, she was keeping it to herself.

Anya Burba was stashed behind the closed door of the head teacher’s office. Her sharp features were swollen with tears, her make-up streaked and ugly. ‘Ashley texted me,’ she said as soon as the head left them alone with her. ‘I couldn’t believe what she says. How can Nadia be dead? How is this possible? You must have made a mistake.’

‘Sorry, Anya. There’s no mistake. I’m very sorry for your loss.’ Fielding’s sympathy was underscored with briskness. ‘We need your help so we can find the person who did this.’

They sat at a round table in a corner of the office. It was strewn with children’s artwork. Anya cleared it impatiently to one side with a sweep of her arm. ‘Stupid art competition,’ she said, her voice shaky. ‘How did she die?’

‘We can’t go into details, I’m afraid,’ Fielding said.

‘Was it quick? Tell me she didn’t suffer.’

Paula reached out and touched her shoulder. ‘There’s a lot we don’t know, Anya. But Nadia was your friend and we need you to share what you know about her so we can stop this happening to somebody else.’

She shivered and wrapped her thin arms round her body, pushing her small breasts upwards. ‘Please God, not that.’