It happened in broad daylight, one April afternoon in 2015, while the citizens of an outer-western Melbourne suburb called Wyndham Vale were peaceably going about their business.

A chef, on her way to get a tattoo, was driving past Lake Gladman, a reedy, rock-edged suburban wetland, when the blue Toyota SUV in front of her suddenly pulled off the bitumen and stopped on the gravel. As the chef drove by, she caught a glimpse of an African woman sitting huddled over the steering wheel with her face in her hands. Kids behind her were rioting: a little one was thrashing in his booster, a bigger one dangling off the back of the driver’s seat. Minutes later a passing teacher saw the Toyota “drive full bolt, straight into the water”. A man who lived opposite saw it hit the water; he heard splashing and wheels spinning as the vehicle moved further into the lake. A young boy raced home on his bike: “Mum! There’s people in the water!” Someone was screaming – a long, wordless wail.

A sales manager ran out of his house and waded into the lake. The water wasn’t deep enough to engulf the car. Its roof was still above the surface, but it was filling fast. The driver must have scrambled out through her window: she was standing beside it in the water. The frantic salesman tried to break one of the rear passenger windows with his fist and his elbow. It wouldn’t shatter. He yelled for a rock. A courier on the bank tore off his steel-toed boot and chucked it to him. He smashed the window and fought one child free of his harness. The hysterical teacher on the bank, crying out to triple-0, saw another kid on his back in the water, trying to keep his head above the surface, but sinking. Rescuers were shouting to the mother: Were there more children? How many were there? She stood silent beside the driver’s door, gazing straight ahead.

Her name was Akon Guode. She was a 35-year-old South Sudanese refugee, a widow with seven children. Three of them drowned that afternoon: four-year-old twins Hanger and Madit, and their 16-month-old brother, Bol. Their five-year-old sister, Alual, escaped the car and survived.

What Guode said, when the police questioned her, was so vague, so random that the word “lie” seemed hardly to apply. She denied everything. No, she had not been to the lake. She didn’t even know where the lake was. She was going to Coles to buy some milk. On the way to the supermarket she took the children to a park, to play. She meant to drive home, but she became dizzy. She missed the turn and went straight ahead. She didn’t know how she ended up in the water.

“Dizzy”? Such a feeble word, so imprecise, so unconvincing. Her teenage daughter said it. The father of the dead children said it. People turned from their screens and looked at each other with round eyes. Hadn’t we heard this before? Was it a copycat thing? I asked a police investigator who worked on the long and gruelling murder trials of Robert Farquharson, the father of three boys drowned in a dam in 2005, whether he had been having flashbacks. “No flashbacks,” said the detective calmly. “But a very strong sense of déjà vu at the scene.”

It would be hard to imagine anything that looked less like an accident. Not only were there eyewitnesses to the deed, but six houses along the shore of Lake Gladman are fitted with CCTV cameras. The police had been able to put together, with a few small gaps, a video recording of the fact that the mother had driven along the lake five times that day before she planted her foot and went into the water. But Guode pleaded not guilty to all four charges: one of attempted murder for the girl who survived, and three of murder for the twins and for the boy who was not yet two years old.

Like several of my women friends, I flinched from the story yet followed the media reports out of the corner of my eye. We emailed each other, we texted, about women we had known (or had been) – single mothers who slammed the door and ran away, or threw a screaming baby across a room, or crouched howling with one hand on the phone, too ashamed to call for help. The flashpoint was the glimpse that the chef had caught as she drove past the clumsily parked Toyota: the frantic mother hunched over the steering wheel, going off her head while in the back her children went berserk. “How many times have I been there?” whispered my neighbour, a grandmother. “I have to know why she broke.”

I heard that at the committal hearing, in June 2016, Guode collapsed wailing in the dock. Her counsel had to get down on the floor with her to comfort her. The magistrate found the evidence against her sufficient to commit her to a trial by jury.

Then, at the turn of the year, I heard that the Crown had agreed to change the third murder charge, of the toddler, to one of infanticide. Once she was arraigned on this new charge, Guode pleaded guilty to all four counts. This meant that there would be no jury trial, but just a two-day plea hearing in the Supreme Court before Justice Lex Lasry, who in 2010 had heard Robert Farquharson’s excruciating second trial and given him three life sentences, with 33 years on the bottom.

The court documents tell Akon Guode’s story in broad strokes. She married in South Sudan as a teenager. By the time her husband, a soldier in the rebel army of South Sudan, was killed in the civil war she had two children. As a widow in a country where Christian and African traditional customs often blend, she could never remarry. She would remain a member – or perhaps one could say a possession – of her late husband’s family: she was given to one of his brothers. “This is customary once the husband dies,” explained an “auntie” of Guode’s at the committal, through an interpreter. “You don’t go out. You don’t go anywhere else. You stay with the same tribe because you got married for cows. As a dowry.” Guode’s third child was fathered by a man we would think of as her brother-in-law.

With the three children in tow, she walked to Uganda in 18 days, foraging for food along the way. When they got there, another of her late husband’s brothers, already living in Australia, offered to sponsor her and the children: she was granted a global special humanitarian visa. They arrived in Sydney in 2006 and stayed with the brother-in-law until 2008, then moved to Melbourne, where the cost of living was more manageable, and were given temporary shelter by her late husband’s cousin Joseph Manyang, his wife and their three children.

Manyang helped Guode settle into a rented house of her own. Soon she and Manyang, unknown to his wife, began a relationship. In 2009 Guode gave birth to a girl, Alual – the only child who, six years later, would emerge alive from the car in the lake. The family name on the baby’s birth certificate was Chabiet, that of Guode’s late husband.

“You had no idea you were the father,” Joseph Manyang was asked at the committal, “until the child was one year old?”

“I asked her about the father of the child,” said Manyang. “She told me, ‘I can’t tell you.’”

It was confirmed by a DNA test, after the day of the lake, that the child was his.

The relationship continued. In 2010 Guode had twins, a boy and a girl. By now Manyang’s wife was no longer in ignorance. She felt it sorely; she raged. Later, in court, she would deny that she came to Guode’s house and beat on the door, shouting insults and threats while the family lay low inside. There was an unpleasant confrontation at a shopping centre. Manyang moved out of the marital home and set up on his own. He visited each woman and her set of his children once or twice a week. The community hummed with rumours. Guode’s link with Manyang, though it had been so fruitful of offspring, could never be officially recognised: she was obliged to remain forever a widow. Could she have gone on hoping that the relationship had meaning, and a future?

Guode was running her household on Centrelink payments and on Manyang’s sporadic contributions. In 2012 she worked for 12 months at a family day-care centre. Like most refugees she was regularly sending back as much money as she could spare to her parents and her extended family in Africa. Then, in 2013, she became pregnant again. Shortly before the child was born, Centrelink, in a contretemps about an overpayment, suspended her benefits. A repayment scheme was eventually put in place, but she was barely squeaking by from week to week.

Meanwhile, somehow, her six children were well cared for. Their education mattered to her: they went to school, they did their homework. Akoi Chabiet, her eldest child by the husband who had been killed in the war, was an assiduous helper in the house and a keen high school student. The girl had plans for a life. She wanted to go to university, and was prepared to work for it.

Guode went into labour on 21 December 2013. Because she already had more than five children, she was what is known in midwifery as a grand multi. The birth of a child that follows caesarean twins, as hers had been, is always high risk, and the hospital was ready for it. But things did not go smoothly. After she had given birth she kept bleeding, and they could not stop it. A consent form for whatever life-saving treatment might be needed was brought to her. She signed it. By the time they got her to the holding bay outside theatre, where the doctors were waiting for her, her haemorrhage had reached emergency proportions. “I remember the linen underneath her,” said the midwife at the committal, “being quite soaked with blood, and I remember her looking down and being aware of the blood loss herself.”

But in the holding bay she said no. She flatly refused to go through the door. They couldn’t understand it. Three doctors tried to explain to her what they might need to do. She would not give eye contact. She kept holding up her hand and turning her head away, saying, “No. No.” She wouldn’t let them phone the man she referred to as her “husband”. Staff rang every number they could find. Many of them were incorrect or disconnected, or the calls were picked up by young children. They got through to a sister-in-law, who backed Guode in her refusal. Then, for some reason, Guode ran out of fight. She surrendered. They wheeled her in. She had lost half the blood in her body. As part of the full resuscitation they had to give her, to prevent her from going into shock, they inserted an intravenous cannula into the internal jugular vein in her neck. They managed to save her without surgical intervention.

Around Christmas 2013, Guode made it home with her new baby, a boy called Bol. Postnatal checks of mother and baby raised no concerns, either physical or psychological. None of her other children’s births had brought on postnatal depression, but plainly Bol’s birth and its aftermath had knocked her around emotionally and psychologically. She thought her debility was due to the cannula that had been put into her neck. She complained occasionally of headaches and dizziness. Often she could not get out of bed. She slept all day and was unable to do the work of a mother and a house-keeper. She became distant from her children. She stopped going to social events. Her community, she felt, was turning its back on her. Rare visits from other Sudanese women she experienced as meddling rather than assistance. Gossip intensified. When Bol was six months old Guode had to ask Manyang to undergo a paternity test, to put paid to rumours that he was not Bol’s father. The test showed that he was.

Manyang’s visits, according to Guode’s daughter Akoi, had tapered off during the pregnancy. By now, Akoi said, he was offering little help with household matters or child care. He was busy with his own concerns: he had two jobs, and would occasionally call Guode from work. He seems to have lost interest in the sad, overburdened woman. The one who picked up the slack was Akoi.

Akoi’s teachers, sympathetic women, began to notice that the girl was distracted, even disengaged. Her schoolwork was falling away. She began to turn up late. When they investigated they found that as well as studying for her Year 12 exams she was running the entire household, shopping, cooking, cleaning and washing, as well as managing the diabetes of her little sister Alual.

Akoi described her mother as “ill”. Her teacher suggested “depressed” as a more accurate term; she tried and failed to find a support group in the area for Guode. She thought there might be a stigma against mental illness among Guode’s people. Indeed, a leader of the South Sudanese community, a respected lawyer who is held in equally high esteem in the world outside it, told the committal hearing that Sudanese people “are highly unlikely to suffer … mental illnesses, due to a chain and a web of support that surrounds us individually and as a community. So when someone … is in trouble, whether they have seek or not seek, and people notice, people will go out and support that person, and they will go above and beyond.”

Joseph Manyang told the committal that he had had no idea Guode was in financial trouble. He said that if she had asked he would have given her money. But by March 2015 the debt collectors were after Guode for unpaid phone bills to the tune of hundreds of dollars, and for gas and power bills that topped $3000. To Centrelink she owed $12,000. Between 2008 and the day of the lake she had managed to send tens of thousands of dollars back to her family in South Sudan, and her obligation to provide money was ongoing. At the committal, the community leader, loyal to his people, disputed this point: “It is not an obligation. I would call it a moral duty.” Under the circumstances, this seems a very fine distinction.

Call it what you will, this woman had been reduced to little more than a conduit for babies and for money. Is it any wonder that she laid her burden down and turned her face to the wall?

Down in Gippsland, where many Sudanese families have settled, Guode had a friend who was fond of her, an “auntie” from her mother’s side called Abook Kon. She worked as a school crossing supervisor for the Latrobe City Council. A woman of resolute address, Kon spoke briskly to the committal about Guode’s pain at Joseph Manyang’s neglect. “She had no right to be upset, because here she’s not married to him. He’s married to another lady. She had no right to be upset … He can father her kids, but she can’t be upset because he’s not spending time with her … The other lady has the right to be upset – Joseph’s wife.”

But Kon had seen how unhappy and lonely Guode was in Melbourne, and suggested she move with the children to Morwell, in Gippsland’s Latrobe Valley, where there was plenty of government housing. Guode had said she would wait till Akoi finished Year 12, and then make the move. Over many months she put it to Manyang. He would not have a bar of it. He would have to make a two-hour drive to see his children: it was too far. But Auntie Abook worked on him, and in the end he agreed that they could go.

This plan gives off a strange static of unreality. Nobody mentioned it in the aftermath of the drownings. Even Homicide didn’t learn of it until many weeks into their investigation. They found that Guode had given notice to her landlord, but had not told the school that her children would be leaving. Perhaps it was only a fantasy of rescue, a dream? She was in no state to handle the logistics of a wholesale domestic uprooting. She had seven children, the youngest only a toddler. She had no husband beside her, and no right ever to seek one. She was exhausted, isolated, mentally ill – poleaxed by postnatal depression. She was losing her grip.

A faint clink of cuffs at the door from the cells, and in she came. In the shots taken at her children’s memorial – her head bound in black cloth, her skin gleaming in candlelight, her eyes distant and dull, her mouth half open as if to gasp or groan – she had been a figure from ancient myth, massive and block-like. Now, ushered past us to the dock for her plea hearing, she was a prisoner in a modern story: bare-headed, her hair cropped, in charcoal top and jeans too short for her long legs. Her skin had lost its lustre: it was matte, reflecting no light. Between the interpreter and the glaring-blond, gum-chewing security guard, Guode took her seat and was swallowed up in the court’s dark timber.

The prosecutor, Kerri Judd QC, laid out the Crown case. On a smartscreen she drew with one finger a wobbly blue worm that traced the wandering path of Guode’s blue Toyota on the afternoon of 8 April 2015. At 1 pm Guode loaded the four youngest children into the car and set out, telling Akoi they were going “to visit Grandma” and to take Alual to a medical appointment for her diabetes. But they went instead to Manor Lakes Boulevard in Wyndham Vale. She drove in several slow, random passes along the lake and back and along again. At 2.18 she called Joseph Manyang. He did not answer. At 2.45 her mother called her from Sudan and they spoke for several minutes. She paused at a park and briefly let the stir-crazy children out to play, then drove on. Just after three, Akoi called her twice. Guode said she would be home soon. At 3.40 the passing strangers saw the car airborne and heard it hit the water.

Judd, a straight-backed woman with an elegantly boyish haircut, ran through these facts with a crisp clarity. After each demonstration of the gap between the evidence and the account Guode had given the police, she would raise her head from her notes and look directly at the judge. When she reached the account of the man who smashed the window and hauled out Bol, already frothing at the mouth, a soft, low sound flowed through the court. It was Guode, keening: she leaned forward on her elbows and wrapped her arms around her head. People did not know where to look. They covered their eyes and turned away.

The thrust of the Crown’s opening was that Guode’s crime against four vulnerable and helpless children – this “gross breach of trust” – was “not a quick, spontaneous act”. She had driven back and forth along the lake several times and chosen the only possible entry point. Once in the water she accelerated. She did nothing to save her children or to help strangers who rushed to the scene, but got out through the window, leaving the children inside. She lied to rescuers about the number of children in the car, and she lied to the police investigators. She had shown little or no remorse.

Guode’s counsel was Marcus Dempsey, a light-voiced, tensely composed man with a face as pale as a teacup. His task was to set her actions, or failures to act, into the deepest possible context.

First he named the elephant in the room – “the inevitable comparison with Farquharson”. He dealt with it by quoting a blunt general statement made to a 2004 Victorian Law Reform Commission review of defences to homicide: “While men kill to control or punish their children or partner, women kill children because they cannot cope with the extreme difficulties that they encounter in trying to care for their children.”

In 2004, he said, the law had been changed to recognise that the devastating effects of postnatal depression on some women’s mental health can persist much longer after childbirth than was previously understood. The period of time during which a mother’s killing of a child could be regarded as infanticide had been extended from one year to two. Infanticide carries a maximum penalty of five years’ imprisonment. But no Victorian mother has ever been sent to prison for infanticide. The usual penalty is a community-based corrections order with psychiatric supervision and treatment.

Anyone who has read the sentencing remarks of judges in these rare and dreadful cases would understand their urge to have mercy. But only one of Guode’s children fell into the age bracket for infanticide – poor little Bol, in his booster seat, only the top of his curly head visible to the man smashing the car window with a steel-capped boot. The twins who drowned were four. The girl who survived was five.

So Dempsey outlined a further recommendation by the commission that had not been taken up: that a mother who kills a child under two, but who, at the same time and while suffering from the same mental disorder, kills another of her children who is older than two, should not face both infanticide and murder charges. The line drawn between the two charges in a case like Guode’s, said Dempsey, was arbitrary and artificial. It did not make sense. There was no legal or moral reason to draw it.

“We’re asking Your Honour,” he said, “to view Akon Guode’s conduct through the prism of infanticide, rather than as a murder first with an infanticide tacked on the end.” Infanticide was “at the heart of all her conduct”. Otherwise, he said, what she had done was “inexplicable and unfathomable”.

Dempsey’s account of his client’s life had a stride to it, and more nuance than the committal transcript offered. Her father had six children with one woman and five with another; the families lived in separate compounds. Guode’s was a love marriage. Dempsey sketched the disruption of their lives by the civil war, her move to Eritrea with the children while her husband fought, his death. He described the conditions of the walk to Uganda with her children, in the endless column of refugees: the violence of the soldiers, the ubiquity of rape, these historically documented facts.

The permanent visa Guode has is granted only on grounds of “substantial discrimination amounting to a gross violation of your human rights in your home country” – the kinds of things that qualify as crimes of war. But now, charged with four crimes of her own, Guode had declined to draw on her experiences in the war zone to allow a diagnosis of post-traumatic stress disorder to be made. She simply would not go there. “Typically,” said Dempsey, “she withholds that information when cynically she could volunteer it to extract sympathy or pity.” In short, her lawyers had come up against a roadblock: her character.

At a very young age, it seems, she had learnt from brute reality the pointlessness of protest. She had been obliged to develop what the defence’s forensic psychiatric witness, Dr Danny Sullivan, called “a personality style of extraordinary resilience and stoicism”. And in the face of her many displacements and disappointments she maintained this stoical carapace, said Dempsey, all the way to 2015, by which time she was “utterly broken”.

A guilty plea raises certain crucial questions. Does the person acknowledge responsibility for her actions? Does she feel remorse for what she did? Guode’s impenetrable stoicism made the extent of her remorse almost impossible for the court to determine. And there was a contradiction in her position: although she had pleaded guilty, she continued to insist, in her interviews with Dr Sullivan, that she had never meant to kill her children. “She acknowledges her responsibility,” said Dempsey, “to the extent that her personality permits her to, and still live.”

Justice Lasry pressed Dr Sullivan to point to some specific event that might have pushed Guode over the edge from her “major depressive disorder” – a malaise that everyone agreed strikes much deeper than “normal human misery”, and from which there was no doubt that she profoundly suffered – into a state in which she was capable of killing her own children.

“There must have been something, mustn’t there?” said the judge. “Does it not follow from what she did that there must have been something dramatic which accentuated her condition?”

“In many cases,” said the psychiatrist helplessly, “it can just be the ebb and flow of human suffering, and the person reaching the threshold at which they can … no longer go on.”

No one in a court speaks the language of psychoanalysis, I know, but listening to this description of an ironclad endurance forged in extreme adversity, I remembered a remark by the British analyst Wilfred Bion that had always mystified me but now made sense: “People exist … in whom pain … is so intolerable that they feel the pain but will not suffer it and so cannot be said to discover it.” A woman psychiatrist in Melbourne who has worked with many refugees from the Sudanese conflict had described Guode’s experiences to me as “unprocessed – repressed”. Guode was lost in her own numbness. How could she ask for help, or admit – even to herself – how far down she had slid? A woman with seven children to raise, but with no adult companion to love her and help her and hold her together, is not free to let herself go into grieving for her losses.

And perhaps the trigger event that the judge was seeking was not proximate to the crime, but went back to the existential battering she had suffered a year and a half earlier, at the bloody birth of her seventh child. A moment that still haunts me was Guode in the holding bay, refusing to go into the operating theatre – face turned from the fast-talking doctors, eyes closed, hand up: no, no.

At my first reading of the committal transcript, skimming for drama instead of sifting for fact, I had without hesitation interpreted her refusal as a suicidal dropping of her bundle: I can’t take any more. Let me be, leave me alone and let me go. But the psychiatrist Dr Sullivan had not been able to establish any “suicidal ideation”, past or present, in his interviews with Guode. When court rose that day I went back to the transcript. What I found there rocked me. How could I, as a woman, have failed to grasp the nature of the last-ditch “life-saving treatment” for which they were insisting on her permission? Appalled by the terrible flow of blood, I had thought only of transfusion. But there it was, in prosecutor Michele Williams’ re-examination of the midwife:

“And the … hysterectomy that would be performed if other methods failed … That’s what she was refusing?”

“Yes.”

Could it be that this woman, widowed, passed from hand to hand and abandoned, overwhelmed by her own fertility, estranged from her community and up to her neck in debt, was prepared to risk bleeding to death on a hospital gurney rather than consent to the surgical removal of the sole symbol of her worth, the site of her only dignity and power: her womb?

Surely, a woman whose life had lost all meaning apart from her motherhood would kill her children only in a fit of madness.

If a full-bore jury trial is a symphony, a plea hearing is a string quartet. Its purpose seems to be to clear a space in which the quality of mercy might at least be contemplated. There is something moving in its quiet thoughtfulness, the intensity of its focus, the murmuring voices of judge and counsel, the absence of melodrama or posturing. It’s the law in action, working to fit the dry, clean planes of reason to the jagged edges of human wildness and suffering.

Justice Lasry had made it clear, in his uneasy questioning of the defence’s psychiatrist, that he was not considering imposing a life sentence. Nor, said the prosecutor, would the Crown be seeking one. Now the judge told the court that he had to leave town next morning to hear a murder trial in Bendigo. It would take at least three weeks. He would not be able to turn his attention to Guode’s sentence until well after that matter. He adjourned the hearing early in the afternoon of its second day, and everyone but the prisoner got up and went back to their ordinary lives, to wait for the call.

I have never much envied judges, but for Justice Lasry in this case I felt no envy at all.

What would follow if he were persuaded by Dempsey’s eloquent plea to consider all Guode’s actions under the merciful shelter of infanticide? Imagine the screaming of the tabloids. Weak judges! Soft on crime! These refugees – they come here and think they can get away with anything!

If Akon Guode did go to prison, she would almost certainly have her visa cancelled once she had served her sentence, and would be deported. If the government paid attention to the country reports issued by its own Department of Foreign Affairs and Trade, it could hardly send her back to Sudan, a land racked by civil upheaval and famine, where rape as a tactic in areas of conflict is common and accepted, and women have no protection. The only avenue open to her here would be to apply for a protection visa, and that would be a long shot. Where else could she be sent? Most likely to a detention centre, where she might languish for years, a stateless pariah.

On the train one morning I struck up a conversation with a thoughtful-looking VCE student who was carrying a copy of Euripides’ Medea. I asked her what she made of the famous play. She reeled off the things that students are taught to say about it. I wanted to know if she shared my anxiety. I said, “She did a terrible, terrible thing. But she was very badly treated. She was betrayed. She was —”

The girl flushed and leaned forward. She put out both hands to me, palms up, and whispered, “But she was – a mother.”

I had no reply.

I was troubled, and I still am, by the finality of the word “mother”, this great thundering archetype with the power to stop the intellect in its tracks.

“The herculean task of being a mother,” said Marcus Dempsey in his final submission, “has now fallen to Akoi.”

In the shadow of this ancient duty, so implacable and profound, can mercy hold up its head?

On 30 May 2017, Justice Lasry sentenced Akon Guode to 26 years and six months in jail, with a non-parole period of 20 years. On 16 August 2018, the Court of Appeal reduced her sentence to 18 years, with a non-parole period of 14 years.

Akon Guode’s sentence was initially the subject of an unsuccessful appeal to the Victorian Court of Appeal, and then a subsequent, successful appeal. This resulted in a significant reduction in her sentence – the non-parole period being reduced from 20 to 14 years. This decision was itself then appealed to the High Court by the Victorian Director of Public Prosecutions. The High Court granted the appeal and it was remitted back to the Victorian Court of Appeal for another sentence appeal hearing which is unlikely to be heard until late 2020.