It sounds as if Jeffrey Dahmer is not yet able to see the angel. He is still in despair, his present position confirming his black view of himself as an outsider whose life serves no purpose, who would be better off dead. And yet he did not rest until he had identified all the victims. The police, unable to make official comment, allow the inference that he was not only cooperative but even helpful. “If I can restore names to them all,” Dahmer said, “at least that is something good I can do.”

Nilsen talked about Murder Under Trust, “under my roof and under my protection—the most horrible thing imaginable.” But it was not the most horrible thing he did. Philosophically and emotionally, we must all recognize that we are capable of killing, but we shrink from the desecration of corpses. When I told Nilsen that it was this which defined the gulf that separated him from the rest of humankind, he remonstrated with me and told me my moral values were confused. His reasoning was that, while it was wicked to squeeze the life out of a person, it was harmless to cut a dead body, which was only a thing and could not be hurt. This was, I had to say, logical but inhuman. Respect for the dead goes beyond civilization to the very marrow of our bones, to essential concepts of worth and spirit. It may be illogical, but its absence, to the common man, points to madness.

There was one particular day when I forced myself to face this madness, and my life has not really been the same since. I had previously written about eighteenth-century history or twentieth-century literature, and was quite unused to delving into the dark recesses of mental disorder. I found myself at ease with Dennis Nilsen, and asked the police to show me the evidence of what they had found in his London flat, to remind myself of what he had done. They were reluctant, for they knew what disastrous effect the photographs could have. There were two brown cardboard boxes containing photographs of progressive discovery, starting with the house, then the door of the apartment, then the bath, from beneath which protruded two human legs, then the black garbage bags, and the contents of the bags, and so on. I could look at only twelve of them before I was overwhelmed with pity for these poor young men, reduced to refuse. It breaks one’s heart, too, to think of little Konerak Sinthasomphone, who tried to escape from Jeffrey Dahmer and was brought back, or of Tony Hughes, the deaf-mute who went trustingly to Apartment 213 and might have found no way to protest what was happening to him. These images enter the brain, and nothing can ever dislodge them.

How could Dennis Nilsen, with quasi-scientific curiosity, inform me that the weight of a severed head, when you picked it up by the hair, is far greater than one might imagine? Clearly, to be able to make such a comment, to dismember the bodies of people he had seen when alive, and to continue living surrounded by their pieces, demonstrates insanity. This is the res ipsa loquitur argument—”The thing speaks for itself”—which is circular but correct.

Despite the common sense inherent in the proposition, it is difficult to convince juries of it, because they somehow feel the murderer is thereby being excused. Juries cannot bring themselves to consider that a person can know what he is doing, but have no emotional awareness of it at the time; that if the emotional factor is drained from him he is like an automaton. When Nilsen was convicted in 1983, the jury was initially divided down the middle on the question of his mental responsibility, and came back to seek further guidance from the judge, who introduced the nonlegal and nonpsychiatric concept of evil. “A mind can be evil without being abnormal,” he declared. He seemed more certain about the matter than any philosopher since Socrates, and his certainty sent Nilsen to prison rather than to a mental institution.