‘Do you think it was a website?’

‘Yes.’

Fry made a note of the name. ‘Anything else?’

‘Well, Dad once talked to me about a kind of religion called Santeria. He said its practitioners gave themselves power by digging up a body to remove the head, and the fingers and toes. I think there were other bones, too. I forget which. Another time he talked about necromancy. I thought that was just a way of predicting the future or something, like reading tea leaves. But Dad said it was a means of communicating with the dead. There was a ritual to perform. But it had to be within a year of the person’s death, because that was how long the spirit hung around the body.’

‘Did he go into any more detail than that?’

‘No.’ Mrs Somerville hunched her shoulders and folded her arms across her body, as if she suddenly felt cold. ‘I gave him a piece of my mind then, told him to pull himself together. I said he was getting obsessed and should ask for professional help. He shut up, and didn’t mention it again.’

‘I don’t suppose he ever did seek help?’

‘I doubt it. He just shut himself up in his house, with his library and his computer.’

‘Mrs Somerville, do you have any reason to believe that your father took his interests further than theoretical research?’

‘How do you mean?’

‘Do you think he ever tried to put some of those rituals into practice?’

She swallowed, but shook her head vigorously. ‘No, no, he would never have gone that far. Dad isn’t a practical man, you see. The details would be quite beyond him.’

‘But if he used the internet a lot, he might have made contact with people who were more practical – individuals keen to exploit his interests. Did he ever mention anybody like that?’

‘No, he didn’t talk about anybody else. Do you mean, people who might … supply him?’

‘There are individuals who’ll provide any service, for the right money,’ said Fry. ‘I presume Professor Robertson is reasonably well off?’

‘Yes, he has plenty of money put away.’

‘Are you sure he never referred to anybody else? If you remember anything, even the smallest hint, please tell me.’

‘No. I don’t think he had direct contact with many people, after the courses finished.’

Fry had been about to get up and leave, but she stopped. ‘Courses?’

‘He had a little group of students at one time who came to him to learn about Thanatology. I think they were a sort of off-shoot from his university work. But they stopped coming when Mum was very ill. Dad didn’t want anybody in the house then.’

‘They used to come to the house?’

‘Yes, he gave private tuition. I don’t think there were more than half a dozen of them.’

‘Do you know any names?’

‘No, I never met any of them. But, please – I haven’t explained yet why I wanted to come in and see you tonight. You see, I spoke to Dad earlier today, and he sounded odd, not himself at all. I thought he was ill, but he told me to stop worrying. I didn’t believe him, so I arranged to go and visit him this evening in Totley. I wanted to see him for myself and assess his – well, his condition.’