‘He forged the will of his last victim, completely excluding the old lady’s children and grandchildren, but giving Shipman several hundred thousands of pounds. He’d never done that before. Was that last move a sign that he was incredibly reckless? It’s possible. But if he was so reckless I doubt he would have been able to kill undetected for so long.’

‘So you really think he wanted to be caught at the end?’

‘It’s not unusual. Going back to the characteristics of serial killers – the known ones at least – it’s quite common for them to crave attention. Often they’re loners. Killing, for them, brings a feeling of great power. But sometimes it’s not enough just to experience that feeling in the moment. They need to share it with others. One of the ways a killer can do that is to get caught.’

‘And another is to leave notes,’ Dani said, feeling her heart thump a little faster.

Grant studied her for a few moments, as though he sensed the words were important to her.

‘Yes,’ he said eventually. ‘That’s also relatively common. Calling cards, if you will, but also sometimes out and out taunts. Have you heard of the BTK killer?’

‘Actually, no. I may investigate murder for a living, but reading up on serial killers has never been much of a hobby.’

Dani thought she saw a flicker of embarrassment on Grant’s face, as though her words had made him feel slightly ashamed of his obvious passion for the subject. He wasn’t derailed for long though.

‘The BTK killer – an acronym for bind, torture, kill – was a notorious American serial killer,’ Grant carried on. ‘He killed ten people between 1974 and 1991. Gruesome killings, as you can imagine from his moniker. Yet he remained free for years, despite the fact that he regularly left taunting notes for the police, admitting and explaining what he’d done. These notes were often left in public places, because he absolutely wanted attention for being a serial killer. If he’d never left the notes? Maybe the deaths wouldn’t have been linked at all. Perhaps he could have carried on killing with impunity.’

‘The notes led to him being caught then?’