“Evil” is an overused word. Because of that, it is sometimes inadequate, as in the case of Sarah Everard, though no other word will do. Her final hours and minutes: one’s mind recoils from the horror. Yet think of her family. For them, there can be no recoiling. They too are facing a whole-life sentence, of pain and grief, which will only end with death.

The public revulsion is understandable as is the call for action. There is a widespread insistence that something must be done and that someone is to blame. Implicit in all this is a belief that if matters had been handled better, Miss Everard would still be alive. But there are problems. Outrage in search of easy answers will not solve difficult questions. Suppose Couzens had never been on duty in Westminster. Suppose he had been prosecuted for flashing. Suppose a senior police officer had asked whether a man nicknamed “the rapist” was fit to be a policeman? One suspects that Couzens would still have found his way to rape and murder. Again, strong words are worn down by excessive use. The word “monster” makes one think of children’s fiction. Yet there are real two-legged monsters, who can live in society while using their human skills to search out their prey. Can they be identified before they turn into predators? Perhaps Couzens and others like him should be studied by psychiatrists to see if they can provide clues.