AS if to highlight the turbulence and unpredictability of the times in which we live, so far this year the crime pages have been dominated by three extraordinary cases.

It is not the nature of these cases that is unusual -- though they are, at the very least, unpleasant to recount; a child abduction, a sexually motivated murder and a case of incest and child rape. Something else distinguishes them from the roll call of horrors that is a regrettably accepted aspect of our world. What is most odd about them is that in all three, the accused are female.

In the past few weeks, our eyes have been on Britain, where Karen Matthews was jailed for co-ordinating the kidnap of her own daughter Shannon. And on Italy, and the trial of 21-year-old Amanda Knox, who is charged with the murder of her flatmate Meredith Kercher in Puglia. But of these three cases the one that is perhaps the most inconceivable happened right here at home. Last month, an unnamed woman from Roscommon was sentenced to seven years in jail for the appalling neglect of her own children and -- most shockingly -- the sexual abuse of one of them.

In this age of rolling, international news, it is a sad fact that we have become habituated to seeing these sorts of crimes on TV and in the newspapers. We feel familiar with the drill, from the first announcement, to the police press conference, to the shots of a (usually) male, pasty-faced perpetrator being led from court to prison. The ensuing public reaction follows a predictable trajectory. We move from outrage and disgust to sadness and eventual relief as the person responsible is finally driven away to jail.

It's a cathartic emotional ritual which we share in instinctively, and appropriately. A fundamental part of an effectively functioning society is the collective identification, and casting out of those individuals who pose a threat. It is reassuring to observe this process happening. Though we might be ashamed to admit it, it's even more so when the bad guy looks the part. A furtive looking, trench-coated male fits our preconceptions. We feel safer knowing we can identify danger.

But what happens when evil has a different face? When it disguises itself as soft and vulnerable? As female, or even more confusingly perhaps, as a beautiful young girl? Women are the more vulnerable gender. As such, (along with children) they are the very ones that it is society's primary role to protect. When they are suspected of turning predatory, it confounds all our expectations. We feel our instinctive responses have failed us, and that we are out of our depth.

As a result, as perpetrators of abuse, exploitation and violence, men and women are treated differently. When they abuse and damage, men violate acceptable social boundaries because, our intuition tells us, they have succumbed to their baser, animal selves. It's wrong, of course. But in some primal way, we believe it to be not entirely out of accord with nature. Not so for women.

Women who behave the same way are not considered to be simply brutish, or base, or damaged. For them to cause harm to other women or even to children crosses into a whole new territory of taboo. They cannot be understood according to our sense of the natural order of things, so they have to be seen as freaks. This is clearly apparent in the way in which the media, and the public, cast women like Matthews, Knox and the unnamed Roscommon mother as stock villains, as emblems of evil. As a gut response, this is understandable. But it is also irrational, reductive, and through its lack of concession to reason, harmful to the cause of properly understanding the complexity of these acts.

Karen Matthews, the Yorkshire mother who abducted her own child in order to claim a £50,000 reward, was last week sentenced to jail for eight years. In February of 2008, she sparked an enormous manhunt and national media campaign when she reported her daughter missing. After eight days, £3.2m of police resources and the mobilisation of a national media campaign, nine-year-old Shannon Matthews was discovered, safe but drugged and frightened, underneath a divan bed in a flat that was the residence of Karen Matthew's partner's uncle. The whole situation was bafflingly convoluted and further obfuscated by the fact that, when interviewed by police in connection with the case, Karen gave them no fewer than five conflicting accounts of what had happened. Eventually, she settled on placing the blame on the man who was her partner at the time of the kidnapping, Craig Meehan. She claimed that he was physically abusive to her and that she had acted on his command, and out of fear. Charges have not been brought against him in relation to the case. He is, however, currently doing time for the possession of child pornography -- discovered on his computer by officers investigating the disappearance of Shannon.

Since all of this came to light Matthews has been named the most hated woman in Britain. She has been pilloried in the press, and subject to the sort of venom rarely seen since Myra Hindley stood in the dock.

The case in Roscommon is one of a handful that has garnered public outcry of comparable proportions on this island. When the details of the "house of horrors" emerged during the trial in recent weeks, and a 40-year-old woman earned the damning distinction of being the first woman in the history of the state ever to be convicted of incest, the news rocked the nation. Of course, a key factor in the public's reaction to these two cases is that these criminals are not simply women; they are mothers and their victims are their own children. Malevolent intent always seems much more sinister when it originates from those people responsible for protecting and caring for others. Doctors, social workers or police officers who do wrong against their charges are considered more dangerous than ordinary Joes who commit the same crimes. Mothers who abuse or harm are considered to be not just bad or broken, but inhuma too. Only a monster, we seem to feel, could transgress the laws of state and decency so egregiously, and so sacrifice the welfare of her own children.

The same does not apply to fathers, but perhaps there is good reason for this gender distinction. As principle carer and source of succour, mothers who turn against their children arguably do more damage than fathers (or other men) who do the same. Perhaps if they have at least a solid and nurturing primary relationship in place, child victims can have hope for recovery and ultimately functional emotional health.

The Roscommon and the Shannon Matthews cases might differ in the degrees of wrongdoing involved, but they both represent much more than a dereliction of duty on the part of the mothers in question. They suggest a wilful, deliberate, and even sadistic desire to cause harm. Or at least, a level of dispassion that crosses into the realm of the psychopathic. They have demonstrated an epic evil rarely seen outside the pages of Greek tragedy.

From a moral perspective, their crimes are no worse than if they had been committed by men. But since their behaviour violates every sense we have of the appropriately feminine, we can only make sense of it by fashioning them into corrupt caricatures. So Karen Matthews becomes recognised as a sink-estate low-life -- a malign parody of Waynetta Slob. When Frances Oldham QC, defending Karen Matthews, cautioned obser-vers in court of the danger of demonising a "stupid and inadequate mother" into a monster, it was already too late.

The Roscommon woman is not merely a stupid and inadequate mother. She has come to be seen as a sort of anti-mother -- a chronic alcoholic whose addiction and selfishness rendered her so morally and functionally squalid as to be dehumanised.

As yet we know nothing about her own background, or the circumstances of her upbringing. But all of these things are being treated as an irrelevance in our rush to cast her as an archetype of evil.

Amanda Knox, for her part, has not yet even been found guilty of the charges on which she has been arraigned. Still, coverage of the Meredith Kercher trial has focused almost entirely on the still indeterminate role she is alleged to have played in the British girl's death.

Since the moment that the details of the killings emerged back in late 2007, all reporting of the case has focused on the central character of Amanda Knox.

The body of 21-year-old language student Meredith Kercher was found underneath a blood-soaked duvet in her bedroom in the flat she shared with Amanda Knox. It is alleged by the prosecution in the case that she was murdered as part of an elaborate sex game involving Knox, her boyfriend Rafaelle Sollecito and another man, Rudy Guede. DNA evidence proved that Guede had sex with Kercher before she died. Guede claims the sex was consensual. Regardless, last year his trial was fast-tracked and he was found guilty of conspiracy to murder, and sentenced to 30 years in prison.

As the events unravelled on newswires around the world, the character of Amanda Knox was thrown into relief. An affluent language student from Seattle, she obstructed the police inquiry by providing numerous accounts of where she had been when Kercher was murdered. Though initially admitting to having been in the house when it happened, she then changed her story, claiming to have stayed all night with her boyfriend. This evidenced at the least, a scheming, evasive approach to dealing with the police. Titillating detail about the girl provided courtesy of her Myspace page quickly began to add up, however, to trial by media. For one thing, she had admitted to using drugs. For another, she once had written a short story involving a rape.

Some seem to have openly revelled in the notion of Knox as a glitteringly beautiful, cold-hearted murderess. Despite the fact that Guede and Sollecito are equally implicated in the case, by far the most compelling aspect of the story is the character of "foxy Knoxy". Dark though it may be, her alleged involvement in a sexually motivated murder affords her a grim sort of glamour. It is a distasteful corollary to this morbid fascination that Knox has been voted as woman of the year in a poll in Italy.

The gender-based double standard where predatory women are concerned is a well-recognised phenomenon. It's why Myra Hindley stands in history as an emblem of evil while the name of the man she assisted, Ian Brady, carries only a fraction of the fame. It's why Maxine Carr has been subject to as much, if not more public outrage than Ian Huntley, the man whose crimes she tried to cover up. Women gone bad have always seemed more transgressive and further beyond redemption than men who commit the same crimes, or even worse ones. Since we generally believe that women are biologically programmed to be more empathic than men, we expect them to have a more finely developed understanding of the pain and the damage that cruelty on this scale will cause, and to be less able to distance themselves from their victims. Therefore, the logic follows, for them to behave in this manner must mean that they are infected with incurable evil.

There are certain abiding characteristics that are regularly highlighted as further evidence for such an infection. Vanity, avarice, and, that old stalwart, sexual promiscuity go hand in hand with the archetype of demon woman. Since medieval times it has been ever thus. And the tone of the media coverage of these three cases proves just how much these notions are still in currency today. Karen Matthews, the tabloids have shrieked, was the sort of woman who would trade in her daughter for a flat-screen television. Amanda Knox, the prosecution would have us believe, is the kind of girl whose own narcissism was so great it prevented her from putting any value at all on the life of her friend. Her self-styling as the sexually adventurous Foxy Knoxy has been trumpeted with all the fanfare of supporting evidence for the prosecution.

There may be some truth in these connections. But they are also only one part of the story. In reality, there can be no doubt that there are far deeper more complex motives, causal factors and levels of damage and culpability to be excavated from the minds of each of the defendants in question.

We need to put aside the caricature for the sake of a balanced and concerted effort to understand the reasons that might drive any person, male or female, to inflict this sort of harm. To see them as demons might provide us with the satisfaction of moral clarity. But it also prevents us from properly analysing the psychological roots of these behaviours. And that process, however clumsy and slow, offers our only hope of one day determining how to prevent such horrors from happening in the first place.

- Julia Molony