‘It’s really not that complicated. A VPN tunnel is an information channel that encrypts all data transported through it, which makes it impossible for a third party to check the content. The problem is that the sender address and the recipient address at the beginning and end of the tunnel aren’t anonymous, so they can be traced with the right software. To get around that, Comorowski’s added a so-called TOR router to the signal chain – The Onion Router, as it’s really called. It anonymizes both the sender and the receiver by bouncing the information back and forth between proxy servers. That way, he’s not only made sure the contents are undecipherable to any prying eyes, he’s also made it impossible for us to trace him.’

‘So the only thing you’ve found out is that we can’t find out anything else.’

‘That’s another way of putting it.’

Tuvesson did nothing to hide her irritation. ‘What about that tattoo, then? Did any of the other women have one like it?’

‘Unfortunately not,’ Fabian said.

‘That means we have to drop the hypothesis that Christofer Comorowski and Columbus are the same person.’

‘Isn’t that a bit hasty?’

Tuvesson shrugged. ‘As far as I can see, there’s nothing to suggest a link between them.’

‘No?’ Fabian said. ‘We have one bloke installing hidden webcams in the homes of single women and another who moves in the swinger circuit, branding women like cattle after having sex with them. I would say there are plenty of points of contact.’

‘One sounds more like a voyeur and the other more like a practitioner, if you ask me.’

‘Perhaps. At the same time, though, there are countless examples of observers tiring of sitting on the sidelines and deciding to get involved. And we have the names. I know it sounds far-fetched, but Christofer Columbus. It just can’t be a coincidence.’

‘Why not?’ Lilja asked.

‘Because I think we can assume Columbus is a name someone’s given themselves, and self-given monikers always have significance, whether conscious or subconscious.’

‘All right, let’s keep that door open for a while longer. After all, you have a few more names on your list,’ Tuvesson said. ‘Make sure you contact them as soon as possible. It might be that some of them are branded.’