It’s the visit that we all hope we'll never experience. The police arriving at your home to tell you that a family member has been murdered. For Marian Partington, 20 years of not knowing what happened to her sister, Lucy, ended with one such visit on a Saturday morning in March 1994.

Lucy disappeared in December 1973 while waiting for a bus in Cheltenham. She was 21 years old and in her final year of an English degree at the University of Exeter. Two decades passed before Lucy was found and the grim truth about her death emerged.

She had been tortured, murdered, dismembered and buried in the cellar of 25 Cromwell Street, Gloucester, along with other victims of serial killers Fred and Rosemary West.

Fred took his own life in prison on New Year’s Day in 1995. In November of the same year, Rosemary was convicted of 10 murders, including those of her 16-year-old daughter, her eight-year-old step-daughter and her husband’s pregnant lover. She was sentenced to life in prison without parole.

“Lucy’s death was about sexual exploitation and cruelty,” Marian said. “Her death was tortured and tortuous. But I couldn’t talk about it without facing the horror of what had happened to her. One huge thing was her not having a voice. Lucy was gagged… I felt if I didn’t speak about what had happened, I might as well be dead too.”

Marian works with a secular organisation called The Forgiveness Project and tells her story to male and female prisoners as part of restorative justice work. In 2004, she wrote Rosemary West – who has become a hated figure in the UK – a letter full of compassion and empathy. West responded by asking her not to be in contact again.

Coming to terms with the crime has not been easy. Marian recalled West’s committal. “I don’t use the word corrupt lightly, but I remember sitting and listening to what she had done… and I could feel myself being corrupted.” Work with female offenders, she said, is particularly challenging.

Women are far less likely than men to commit crimes, but rates of female violence reported in the UK have increased. The number of girls and women arrested for violence more than doubled between 1999-2000 and 2007-08. Whether this reflects an increase in violence per se or in its visibility – or both – is much debated.

The idea of a woman being violent, even murderous, is shocking. But why? Is violence at the hands of women somehow different from that at the hands of men? Regardless, we don’t treat male and female violence the same. Female offenders are often cruelly stereotyped by the media, and they – and their victims – can be poorly served by the criminal justice system.

Female violence is not easy to confront, but a growing number of people are exploring the idea that to rehabilitate women offenders and support their victims better we must move towards a more progressive understanding of what makes a woman harm or kill.

A history of violence

In the past, female power and violence was recognised and even celebrated. Female warriors such as Joan of Arc, Boudicca and the Amazon fighters are iconic. More recently, women in Western and non-Western societies have often taken on leading roles in the military (in the UK, plans are being considered that would permit women in the armed forces to undertake close combat roles from the end of 2016). Women have proved that they are capable of deploying violence in ways that seem to demonstrate choice and agency – sometimes in heinous ways. For example, the Nazis trained half a million women for military service, some 3,500 of whom served as concentration camp guards. A small number stood trial for war crimes.

It was 1997 when I first visited Rwanda, three years after the genocide there. I was struck then, interviewing survivors and perpetrators, and later, when translating testimonies for a charity for survivors, by how many women had been involved. They had taken part as bystanders, instigators and even key figures in the genocide – just as they had in the Holocaust.

The sense of betrayal when women were involved seemed deeper, somehow, because women supposedly shouldn’t commit such crimes. One chilling testimony, which haunted me because it implied such intimate knowledge of childhood, included that women would strew chilli pepper around houses, knowing it would cause any hiding children to sneeze and allow them to be found and hauled out to their death.

Since the 1970s there has been a focus on male violence against girls and women. In many ways that has shifted the framework for characterising violence – particularly intimate and domestic violence – to one that is largely gender-related. This is not surprising – the ‘gender gap’ in recorded crime is well-known. Men commit crime at higher rates than women, are involved more in serious and violent offences (they are responsible for 80% of violent acts) and are more likely to reoffend. They are also more likely to murder their partners, to be convicted of domestic violence, and to commit physical stalking and sexual offences.

None of this means, however, that female offenders do not exist – and how they are treated has become a major part of criminological research. “Some American criminologists had argued that so-called women’s lib would lead to a wave of aggressive crime,” said Frances Heidensohn, a criminologist and visiting professor at the London School of Economics. “Women’s share of crime has increased a bit, but we haven’t seen a big rise… We are talking about a modest contribution to crime and an overreaction to it, with a sensational treatment of perpetrators.”

The number of women in prison in England and Wales nearly trebled between 1993 and 2005. Although that number is now declining, there are still over 2,000 more women behind bars today than in the 1990s, and women make up around 5% of the prison population. At the end of March 2016, over a quarter of the women sentenced in English or Welsh prisons were there for violence against the person. Typically, women commit violence against people they know, often the vulnerable and/or those dependent on their care – children, disabled people, the elderly. Their crimes happen more in private and/or intimate ‘caring’ settings than in public.

Women are also involved, either as bystanders or leaders, in crimes including ‘honour’-based violence, terrorism and human trafficking. In one recent case, a woman narrowly escaped being murdered by a man who wanted to marry her. Disturbingly, a very close female family member of the woman admitted that she and her husband had known of the planned attack and had waited by the phone to hear whether it had been successful.

This is not unusual. A recent report on ‘honour’-based violence, female genital mutilation and forced marriage by Her Majesty’s Inspectorate of Constabulary concluded that both men and women are perpetrators. “Female family members can be involved in facilitating violence and abuse through informal conversation, pressurising males of the family to undertake [honour-based violence] acts or assisting in arranging violence, or actually being involved in the violence or killings,” the report stated.

A recent study published in the Middle East Quarterly also looked at cases where women were involved in ‘honour’ killings. It found that women are both conspirators and hands-on killers in brutal crimes against other women, even their own relatives, and can also be involved in spreading the gossip that can lead to murder.

In the United Kingdom, a growing (albeit still small) number of women are also becoming actively involved in terrorism, as was the case in the 1970s in both Northern Ireland and Germany. In 2014-15, 35 women were arrested for terror-related offences in the UK, treble the number five years ago.

Baroness Helena Kennedy QC, a leading barrister, led an inquiry in 2010–11 into human trafficking in Scotland. “There is a notion that women are not involved in trafficking except as trafficked women,” she said, but that’s not right. The assumption by police and immigration officers arriving at a scene was that they would be looking for male traffickers. But they found women running the massage parlours, saunas and other places where trafficked women ended up. “Some of them were cruel and horrible to other women,” Kennedy said. “In many of the instances that came to light, women had become the managerial class.”

Just like a woman

In May 1993, nurse Beverley Allitt, known in the media as the "Angel of Death", was sentenced after being found guilty of murdering four children and harming several others. On May 5, a UK daily newspaper opined: “Women should nurture, not harm. By and large they do. Even today, violence is a male speciality. But nurses are supposed to be the epitome of female care. They are the angels of newspaper headlines. When women do things like this, it seems unnatural, evil, a perversion of their own biology.”

The paper was summing up what is known as the biological essentialism argument – that women, by nature, are supposedly hard-wired to care for and nurture, rather than to hurt and kill. Men do, of course, commit more violence than women. But are our brains and bodies, through genes and chemicals, responsible for the crime gender gap? Are women who commit violent crimes therefore doubly deviant and, somehow, not really women?

The idea of there being a typical ‘male’ and ‘female’ brain or character is not backed up by current research.

In one paper, Professor Gina Rippon of Aston University and colleagues highlighted ‘non-trivial overlap’ between men and women on traits that are commonly considered either masculine or feminine, such as physical aggression, tender-mindedness and mental rotation. Recent papers by others have characterised the extent of the overlap between men and women. In fact, Rippon said, splitting the people they are studying into ‘male’ and ‘female’ is “actually impeding progress” in gaining any insights into how brain and behaviour relate.

But while male violence is sometimes valorised – in war, for example – or tolerated – as in a pub brawl – it’s rarely the same for women’s violence. We either pity the women who commit heinous crimes or try hard to distance ourselves from them. We do not want to feel any sense of identification. It is too dangerous, even if many of us, if pressed, would admit that we may have on occasion kicked the cat or even smacked our own child. It is almost impossible to imagine such a small, personal act constituting part of a continuum of violence that could lead a woman to kill.

Rather than identify with them, it is easier to class each woman who abuses or kills as exceptional instead. Particular cases are elevated to mythical status, and those who perpetrate them are pitied or vilified, rather than understood. The image created by female offenders can be more powerful, because it is seen as transgressive of gender. It leaves a longer-lasting impression.

Another way to deny female violence is to argue that women act only under the influence of evil men. All too often, women offenders are characterised as ‘mad’ (and so to be pitied, rather than blamed), ‘bad’ (set aside from women as a whole) or ‘sad’ (forced into violence by pressure of circumstance, in retaliation or by coercion).

Typically, a woman who is violent will have her sexuality portrayed as deviant, and her sexual attractiveness – or lack of – examined. Her role as a woman will also be scrutinised – is she a bad wife, or a bad mother? We need to keep the very essence of womanhood separate from, and untainted by, women who kill.

Intimacy and crime

Home is meant to be where we feel safe, somewhere we’re looked after and nurtured, so violence that occurs there, or in other places where people are cared for, seems the most shocking. The traditional focus on male violence in intimate relationships is understandable, as men are more often the perpetrators, and women are more likely to suffer serious injury or die. However, men are not always the offenders, and women not always the victims.

According to the Crime Survey for England and Wales, in 2014-15, 27% of women and 13% of men had experienced some type of domestic abuse since the age of 16, equivalent to an estimated 4.5 million female victims and 2.2 million male victims. Same-sex relationships are no less violent than heterosexual ones. A 2013 study by the US Centers for Disease Control and Prevention found that 44% of lesbians had been physically assaulted by a partner, compared to 35% of straight women. Bisexual women were even more likely to be targeted.

Women are over-represented as perpetrators of hate crimes against disabled people. The latest data from the Crown Prosecution Service shows that women are defendants in nearly a quarter of such crimes, compared to 15% of other hate crimes. This pattern is mirrored in crimes against older people, in which just over one-fifth of defendants are women (although many of the reported crimes are not violent).

And the much-cherished role of mother, key to the identity of so many women, can’t be ignored, especially when it becomes distorted – for example in cases of sexual abuse. Dr Anna Motz, a clinical and forensic psychologist and psychotherapist, explained how difficult it is to scrutinise that role: “We can now talk about women as sexual beings. That has been possible since the rise of feminism,” she said, “but, related to that, women can be deviant and misuse their role as care giver and mother, and it has slowly become more possible to think about it, allow it to be seen.”

Women who act in this way, she said, are seen as unusual and are vilified far more than men who do the same. “The impact on the therapists who work with women who have committed sexual abuse is profound,” Motz said. “They really struggle, so it is not surprising that ordinary members of the public would find it difficult to even countenance as a possibility.”

Estimates by charities working with perpetrators and victims of child abuse vary, but according to ChildLine, a UK charity for children, 17% of its calls from children reporting sexual abuse are about women. The Lucy Faithfull Foundation, which works to safeguard children and young people from sexual abuse, estimates that women are responsible for somewhere between 10% and 20% of all sexual offences against children. But, according to official statistics, only 1% of all child sex offences are committed by women. This discrepancy is likely to be partly because children who say they have been abused by a women are not always believed.

In the UK, in 2014-15 (as in other years), the age group with the highest rate of homicide was children under one – they accounted for 5% of homicide victims but only 1% of the population. The majority of children that are murdered are killed by a parent or step-parent. While mothers are responsible for a large proportion of the murders of very young infants – mothers are more likely than fathers to kill their child soon after birth – fathers are more likely to kill in later childhood. Mothers are also thought to be responsible for almost all cases of (albeit rare) Munchausen’s syndrome by proxy, also known as fabricated or induced illness.

The idealisation of motherhood

Dr Estela Welldon has explored the relationship between mothers and children. This relationship can, at its worst, turn ‘perverse’ and damage children, sometimes irretrievably. Women’s violence, she writes, is directed towards their own bodies or their creations – their children.

“My discovery was about the internal circular motion of perversion," Welldon he said. "When it happens again and again it gives you a new theoretical framework.”

Welldon’s book Mother, Madonna, Whore was banned in one iconic feminist bookstore in north London. Even now, some feminists see her as a traitor to the cause. “I broke new ground and some people do not forgive you for that,” Welldon said, but she stood firm, knowing that her findings came straight out of clinical observations that she felt she could not ignore. “I began to think and listen: ‘What are they talking about? They hate their child…’ It is important to think, and not to judge.”

Welldon’s work has changed clinical practice, and her work at the Portman Clinic in London led the way in treating violent women using intensive psychoanalysis and group therapy.

Psychologist and psychotherapist Anna Motz said that the idealisation of motherhood and the denial of the capacity for female violence can prove a risky mix, particularly for mothers who were damaged themselves at some point. “Women are forced into caring roles,” said Motz, “but can become envious of those for whom they care – vulnerable creatures.” When they have been abused or neglected themselves, she argues, they can re-enact violence on that vulnerable creature, or another who takes that place in their imagination: “a sadistic revenge crime against their own abuser” – in their own minds, at least.

Women who kill or abuse their own child are often trying to annihilate a hated part of themselves, she said, and they see the baby as part of themselves too. In more recent, disturbing work, Motz has started to explore the world of what she calls "toxic couples", where two damaged people come together and create their own family, which gets damaged in turn – most famously seen with serial killer couples such as the Wests.

We view women who kill in domestic settings with horror – except those who are mentally ill, who are seen as defending themselves against domestic violence, or who are carrying out so-called mercy killings of their children. For individual women, this can result in sympathetic legal treatment, but treatment that removes responsibility from them (and a chance of justice for those affected). Men who kill their young children, even if they are mentally disturbed, are very rarely treated with similar sympathy.

To what extent has our propensity to excuse some sorts of female violence allowed some women to, quite literally, get away with murder? In a piece of historical research, criminologists Dr Elizabeth Yardley and Professor David Wilson analysed Mary Ann Cotton, who murdered many of her family members – some sources suggest as many as 21.

Yardley, who dubs such intimate killers "hearthside murderers", said: “She was constantly creating manifestations of the family that she would then wipe out. This feeds into our expectations of women, that they are carers and nurturers, and to a large extent, this hasn’t changed. It is only recently that we have acknowledged that female serial killers, for example, exist. The FBI still thinks of women who kill as reluctant sidekicks.”

Cotton killed alone, for example, and her motive seemed to be money. Yardley added that studies suggest that some 15% of serial killers may be female – an under-representation, but not an absence per se. Recent data for England and Wales reported that in 2014-15, 9% of homicide suspects were women and in 19% of all recorded violent incidents, the offender was female.

Motive and opportunity fuse in the home and other intimate places. In the late 19th century, there were complaints that so-called baby farming had “reached epidemic levels in Britain and not enough was being done to stop it”. For example, Amelia Dyer, considered to be one of Britain's most prolific serial killers, took in illegitimate babies for temporary care or permanent adoption in exchange for payment – but found it easier to dispose of the children in the river. She was caught in 1896 when a boatman hooked the body of a baby girl. She was hanged for murder, after a 30-year career in which she had probably killed 300–400 babies.

Away from the home, other places where vulnerable people are supposedly looked after, such as care settings, can be a place of opportunity for dangerous women. In conjunction with Wilson, Yardley has also carried out research into what are known as "healthcare serial killers", with the most famous British case being that of nurse Allitt. Yardley and Wilson found that there was a growing body of evidence suggesting that healthcare serial killers tended to murder the people least able to protect themselves (such as the elderly or young), were of a more or less even gender split (with slightly higher numbers of female perpetrators), and that most murdered both male and female victims. In all, 63% had a history of mental instability or depression.

“We have been very slow to pick up in social science on women who commit crimes,” Yardley said. “We are still struggling to make sense of women who commit violent crimes such as murder and assault.” She is also particularly interested in looking at the locations where women commit crimes. “It does go back to those gendered themes. Women tend to target people who are dependent on their care. They use that stereotype to get access to those people – the traditional feminine role.”

Working towards forgiveness

Myra Hindley is arguably the UK’s Number One woman folk devil. One half of the Moors Murderers alongside Ian Brady, Hindley killed five children in the north of England between July 1963 and October 1965. As a young woman, barrister Helena Kennedy QC acted for Hindley when she was put on trial after an abortive prison escape.

Kennedy’s book Eve Was Framed, about the injustices women suffer at the hands of the criminal justice system, remains a key text about women and violence, but she is not starry-eyed about the subject. “The Myra that I was seeing was no longer the Myra that was, the ill-educated girl that was in thrall to a very powerful character and sexually intoxicated by him and wanted to meet his needs,” she said. “But can you hang up your moral responsibility? No. She may not have killed children, but she was an enabler; the children might never have got into cars with a strange man. With a woman there, it changes the whole perception of a situation, it makes it seem safe.”

Kennedy thinks that it was right that Hindley was never released, given that Britain does not have the death penalty, although she sets that judgement in a wider context. “Women are less forgiven,” she said. “We live by two sets of rules: the criminal justice system and the other set of rules.” This other set, she said, encompasses the sense that you have done something that runs counter to the rules of womanhood.

“We expect women to be better than men – there is that unspoken thing – that we are more shocked when women do terrible things. I feel it myself,” she said. Kennedy’s analysis goes some way to explain the sheer hatred of women who do break the taboo – or even those who are connected to them, however innocent.

David Smith, who was married to Maureen, Hindley’s sister, witnessed the brutal murder (by Brady and Hindley) of Edward Evans on October 6, 1965, and went to the police, which stopped their killing spree. His later testimony as chief prosecution witness was instrumental in their conviction. Yet, he and Maureen were not only ostracised in the community; they were physically attacked for years afterwards. His account of the day in 1966 that he and Maureen, then heavily pregnant, left their flat so he could give evidence, said: “The crowd’s screams reach fever pitch… I know from experience that most of them are women and many will have brought their kids along… we’re manhandled into the car, the doors slam shut and fists pound on the windows in another unforgettable symphony of hatred.”

It is hard to forgive violent women, castigated as they are for offending twice: once for their crimes, once for breaching unwritten essentialist rules. But there are some extraordinary people who are able to do that.

As impossible as it might seem, Marian is able to talk about Rosemary West, her sister’s torturer and killer, with empathy. Her journey has also helped the family of the perpetrators to move on. Fred’s brother Douglas has been in touch, as has Anne Marie Davis, Fred’s daughter, who was grievously abused.

Forgiving Rosemary West was no easy task. Marian had to make an effort to “humanise her, rather than to demonise her”. But the cycle of violence that Anna Motz refers to made sense to Marian. “When I heard that Rosemary West had been seriously sexually abused by her father and brother and abducted at a bus stop at the age of 16… I get that.” She’s not excusing it, but is trying to understand what it was like to grow up in that kind of environment. “Was there any love? Was it just fear? How could you learn to be loving when you don’t have any love?”

Does the work of people like Marian demonstrate that there can be redemption for violent women? Motz believes so. She spoke of forgiving the offenders with whom she has worked, but added a note of caution. “It is hard for me to be hopeful when people have killed. It becomes difficult for people in that position to ever trust themselves again.”

It takes a personal toll on the therapists too. After 25 years in the field, Motz has taken the difficult decision to leave psychotherapy for a role in consultancy and training related to female offenders instead.

Marian's journey towards forgiveness began on February 16, 1995 when she wrapped her sister’s bones in the mortuary. She lifted Lucy’s skull and kissed the bone of her brow. She then wrapped it in Lucy’s soft brown blanket and laid a sprig of heather on top. An old friend, Beryl, placed Lucy’s childhood toys Chocka and One-eyed Bunny at each side of her skull, with a posy of primroses. Marian then placed a painted Easter egg in the ring of her pelvic bone.

Somehow, we all have to see female violence more clearly, and with more empathy. We have to address it head-on, however hard, rather than just deflecting and distorting it through the prisms of art, literature and the media. That means doing the difficult stuff, and talking to the women who commit violent acts. “It was so important to acknowledge the place of beauty in the world, despite the horror and the atrocity,” said Marian about putting Lucy’s bones to rest. “What we don’t face gets passed on to the next generation.”

This article first appeared on Mosaic.