The public's fascination with women who murder is tangible and much more compelling than society's interest in men who kill. This is partly understandable, since women - the fairer sex - are believed to be incapable of such horror.
The stereotype of the caring, gentle person, capable of giving life and nurturing another person in her womb, doesn't sit easily with the deliberate taking of life.
If those who beget the next generation are capable of destroying them in cold blood, then we have reason to be fearful.
And one of our human needs is to explain what seems inexplicable; to comprehend the incomprehensible.
In so doing, we are providing a psychological insurance policy that will help us protect ourselves and our loved-ones by understanding the mindset and motivations of the perpetrators.
Ultimately, we need to convince ourselves that death in this way could not befall us.
The blanket coverage of the Amanda Knox appeal should not surprise us. It is proof of our preoccupation with women who kill.
Knox, of course, has now been exonerated of the murder of Meredith Kercher (below right), as has her former boyfriend, Raffaele Sollecito.
Yet Sollecito and his family have barely figured in the frenzy of excitement that has followed Knox's successful appeal.
Tempting as it is to attribute our interest in this case to the media - including social media - history is proof that our focus is more atavistic, profound and ancient.
The Bible introduces us to the potential of women for terrible cruelty when King Solomon is confronted by two harlots in a dispute over which one of them was the rightful mother of a child.
The two women lived alone in the same house and had given birth within three days of each other. One of the women told the king that the other woman's child died during the night, because the mother had rolled over on it.
The mother of the dead infant then switched the babies, so that in the morning she had a living son.
The problem was resolved when one woman asked that he divide the baby in two, while the other told him, "Oh, my Lord, give her the living child and in no wise slay it." The one who would give away her child rather than kill it was its mother.
In Renaissance Italy, Lucrezia Borgia was considered a beautiful, but manipulative and ruthless creature, who, in addition to cold-blooded killing, was reputed to engage in sexual orgies with her father and brother.
Ruth Ellis - the last woman to be hanged in Britain in 1955 - was also the subject of much public and Press attention and an appeal for clemency was signed by more than 50,000 people, but rejected by the Home Secretary.
More recently, Myra Hindley, the Moors' murderer, was the most reviled woman in Britain, although that place has recently been taken perhaps by Rosemary West, who along with her husband, Fred, ran the house of horrors. She was found guilty of 10 murders.
In Northern Ireland, Hazel Stewart's trial and eventual conviction for a double murder 20 years ago received widespread attention.
The United States has also produced several women whose actions received worldwide notoriety, most recently those of Casey Anthony, the woman found guilty of murdering her young child. Most of these women have had television documentaries, movies and books written about them.
Both Amanda Knox's original trial and her subsequent appeal received global attention. There were a number of factors that coalesced to make this tragedy so gripping, yet divisive.
The setting was luscious - an Umbrian town, Perugia, with a university dating back to 1308. But even if the name conjures up images of a rural idyll, the actors involved were international visitors from the US, England and elsewhere in Italy itself.
Reports of the murder referred to drugs, sex, knives and copious blood; ingredients that make for compelling, if grisly, attention.
For the public, it almost read like a scene from a Jo Nesbo novel - graphic, but unrealistic. Yet, tragically, it was real for the victim, Meredith Kercher.
The principle character in the investigation was Amanda Knox - a girl from the US on a year's course at Perugia University. Knox was attractive-looking and, at first glance, seemed almost angelic.
Such good-looking women, like Casey Anthony, Ruth Ellis or Lucrezia Borgia, do not commit such evil acts. Their porcelain-like features throw into question our very notion of evil. And the dissonance between our view of what 'evil' people should look like and how they actually look cements our engagement with any process surrounding their actions.
Yet again, we would like the comfort of knowing that creatures, so gentle in appearance, do not engage in vile acts. Now, of course, Knox has been acquitted - and that is a comfort.
But we are still left with unanswered questions about the murder, since two people were supposed to have carried it out.
And history has taught us that, contrary to all our expectations, women do kill - even those who are Madonna-like in appearance.