Although there is almost certainly an element of sexual stimulus in the commission of these crimes, the motivation is not explicitly sexual. The victims do not correspond to any physical class and encompass both genders. It is therefore impossible to predict where he will strike next based on any superficial description of appearance. Contingent on this, and on the scalping of the pubic region (reducing his victims to something resembling a pre-pubertal state) I would suggest that the killer’s own sexuality is relatively unformed. By this I mean that he has never successfully established adult sexual relationships. He may have experienced sexual humiliation at an early age and decided that he was not prepared to expose himself to that again. At some level, he blames this inability to form normal sexual contacts on his victim group. I believe it is highly unlikely that he will be either married or in any sort of long-term relationship. He is most likely to be a single man with no history of emotional relationships with either sex.

So many reasons for the corruption of the sexual impulse, Tony thought sadly. His own experience of impotence, and the soul-searching journey that had taken him on, had given him a unique empathy with those whose natural desires had been morphed into something the rest of the world saw as perversion. There was always an explanation, always a sequence as unique as DNA that lay beneath these strange surfaces, and it was one of the many paradoxes of Tony’s life that what had given him so much personal pain had also given him a professional head start. Maybe, like the killers themselves, he was looking for something that would make him feel less of a failure.

His choice of victims gives him a sense of superiority. People like them have always made him feel slow, unsophisticated. But now he can move into their world, invade their territory and there is nothing they can do to stop him. It is a way of proving to himself that he is not the inadequate he thinks he is. It’s extremely unlikely that he has a university-level education. I would doubt he even completed secondary education, although he is clearly far from stupid. Given what I believe to be his strategy in the choice of victims (see below), it is likely that he has educated himself in their field of expertise. He has probably read extensively about psychology and its applications, both in books and on-line. He may even have taken adult education classes in the subject. He probably thinks of himself as an expert in his field, although his knowledge will of necessity be superficial.

He is capable of a high degree of self-control and organization. To execute his plan, he has developed a strategy of sufficient finesse to convince victims who are experienced in negotiating with the world. In order to succeed at this, he must be able to disguise his unfamiliarity with their universe.

He must have planned this series of attacks well in advance, since the victims require prior research rather than the opportunistic picking at random of a candidate who meets certain physical criteria. It is clear from how close together the last two murders are that he has a preset list of victims. The fact that his time-scale is shortening means that he is growing in confidence but also that he needs more kills to satisfy whatever his agenda is.

What might that agenda be? The answer to that must lie in his choice of targets. What all three have in common is that they are academic psychologists who have published research based on experiments conducted on (willing) human subjects. I believe he entertains the conviction that his life has been blighted as a result of experiments carried out by one or more psychologists. He may himself have been a direct victim, but I doubt that. If that were the case, he would have a specific object for his revenge and it would probably have been sufficient for him to kill that single practitioner. Perhaps he suffered childhood abuse at the hands of a parent or other adult who had been the victim of psychological torture? Given the abuse of psychology at the hands of, for example, the Stasi, this does not seem as improbable as it might in another time and place.