‘But there has been no semen or even signs of penetration found at the scenes,’ Fabel commented. The beautiful Frau Doktor returned his look by angling her face and peering over the top of her glasses.

‘No. But that does not mean that he has not carried out a sexual act. He may have used a condom to prevent leaving DNA traces. What is more likely is that what this person does to achieve sexual gratification is so wildly removed from normal sexual function as to be unrecognisable. And, as I said, he may be impotent. The crime is sexual in nature, but the perpetrator may not himself recognise or acknowledge its sexual motivation. And a major element that emerges from the e-mail – and from the ritualised nature of the killings – is the religiosity of this act. It’s some kind of ceremony he is committing for reasons more abstract than simple or immediate sexual satisfaction.’

Maria Klee interjected. ‘Could this be more than one person? The way you’re talking it’s like it’s almost a ritual. If it’s not political, could we be dealing with some kind of cult?’

Werner Meyer gave a hollow laugh. Both women ignored him. Fabel gave him a warning glance.

‘That is possible, but unlikely,’ answered Susanne Eckhardt. ‘If this were to be the actions of more than one person, then the profile of our principal – the person who is doing the killing – remains the same. Any other involvement would mean a manipulator … someone whose role fills the chasm left by the uncaring or abusive parent. In such cases – like the Leonard Lake and Charles Ng case in America in the eighties – one half of the pair has no self-esteem whatsoever, while the other is pathologically egotistical. But in this case, I think this is much more likely to be a solo crusade. He has spelled that out in his second e-mail. He is a lone wolf. And that, of course, is far more common than teamwork serial killers.’ Dr Eckhardt paused, slipping the glasses from her face. ‘This person is compensating for his low self-esteem through these acts. That is why I think it highly unlikely that Herr Fabel’s terrorist would fit: wrong age, wrong motivations, wrong psychology, wrong politics …’

Van Heiden responded as if he’d received a mild electric shock. ‘What do you mean, “wrong politics”?’

‘Well, the basic psycho-profile I’ve outlined – the blaming of society for personal failings, the belief in a personal potential underdeveloped in an unjust world … almost everything, in fact, excluding the psycho-sexual trauma – also fits with neo-Nazi types.’

‘I thought you said that this was not politically motivated?’

‘Yes. I don’t think it is. This man is probably psycho-sexually motivated to kill, but, like everyone else, he has political opinions. In his case these political opinions may or may not have become grotesquely distorted from his psychotic perspective and may even form a justification – an excuse – for these acts. At least in part. My point is that a left-wing terrorist such as Svensson wouldn’t share the same profile.’