On 4 March 2013, Chantelle Barnsdale-Quean, a 35-year-old mother of two, was killed by her husband of 10 years at their home in Darfield, Barnsley. Stephen Barnsdale-Quean strangled his wife, whose Facebook messages he liked to check and whose debit card he preferred to keep in his own wallet, with a length of metal chain he had bought two weeks before from B&Q. Why did he commit this terrible crime? No one knows. After he had killed Chantelle, he stabbed his face, neck and stomach with a paring knife, the better to claim that she had attacked him; he then suggested to the police that she had committed suicide. “We’re assuming it was about money,” says Chantelle’s mother, Sue. But her voice carries no conviction, for what can anyone say about a man who would do such a thing? Where there should be words, there is only blankness. Where there should be an explanation, some glimpsed understanding, there is only this unspeakable void, as if she had been scoured inside.

Sue and her husband, Stuart, appear in Love You to Death, a film by Vanessa Engle, the subject of which is domestic violence. As well as telling their own story, the couple read out several names from the long list of women – 86 in total – who were killed in Britain by a male partner or ex-partner in 2013. Sue can also be heard at the documentary’s very beginning, claiming Chantelle as her own in the piteous roll call of relationships with which it opens. “She was my auntie,” says the first voice. “She was one of my best friends from school,” says the second. Daughter, neighbour, little sister: every kind of bond is offered up until, with terrible finality, someone says: “She was my mum.” This hour-long accretion not only of names, but of relationships, pushes the viewer to see past the statistics, the miserably stubborn figures in the matter of such killings, which change hardly at all year-to-year. The film is a memorial to the dead, but it’s also a powerful reminder that those who are left behind must somehow live with the knowledge that their son-in-law, their sister’s boyfriend, their father killed someone they loved very much, and that they were able to do nothing to stop him.

Engle, an acclaimed documentary maker whose films (Lefties, Jews, Women and, more recently, Walking with Dogs and Inside Harley Street) are notable for her frank manner when it comes to asking difficult questions, had known about the extent of domestic violence in Britain – on average, two women are killed in England and Wales every week by a current or former male partner – “since for ever”. In her teens, she often went on marches organised by Women Against Violence Against Women. “But however interested you are in an issue, until you have a shape, it’s not an idea,” she says. “It was only when I thought of doing [a documentary about] a whole year of deaths – a unity of time – that I realised I had a film. It was an idea that I borrowed from Morgan Matthews’s The Fallen, [a 2008 film remembering every serviceman and woman who had been killed in Afghanistan and Iraq], and I owe him a great debt.” She would focus, then, on half a dozen or so individual stories, but she would also make sure that every woman who was murdered in the course of 2013 would also be named at some point. The question was: who would read this list?

Cuttings from the Chantelle Barnsdale-Quean murder case. Photograph: Johann Perry/Perry Images Limited

“When my commissioning editor at the BBC asked if there wasn’t an authority figure in the world of domestic violence who could do it, I felt uneasy. I didn’t want to give ownership of the issue to one individual. But as I looked for a solution, it was suddenly obvious: those who agreed to appear in the film would take turns doing it. And then I realised that I didn’t want the viewer only to hear a lot of names and ages. That was too uninflected; they might as well have been breast cancer victims, or people killed cycling. I wanted a brief description of what had happened, and to know how long the couple had been together.”

This decision taken, the hard work began. Eighty-six families had to be contacted. “In the end, 13 were willing to talk to us, three of which later withdrew on the grounds that they would not be able to do it again on camera. For some people, talking to us initially, off camera, had triggered their memories and they simply couldn’t go through it another time. They were too traumatised.” In the final cut, seven families appear, each describing their own unfathomable loss. Watch it, and their stories will be forever burned on your mind.

At the age of 80, Chloe Siokos had her throat slit by her ex-husband of 40 years, after which he doused her body with olive oil and petrol and set fire to her flat. Joanna Hall, 35, was stabbed 40 times at her home in Tenby by her boyfriend of three weeks, a man who refused to call an ambulance for five hours. When she arrived at hospital – she died some days later – her injuries were so bad, doctors believed they would have to amputate her arms. Kirsty Humphrey, from Colchester, was stabbed to death aged 23, after which her boyfriend of nine months simply changed his trousers, put the washing on, and left the house. Her five-year-old daughter, Brooke, who had seen and heard everything – “get up you whore,” he shouted at one point – sat with her body all night. Amina Bibi, 43, was stabbed more than 70 times at home in Forest Gate, east London, by a crack addict her husband of 13 years had paid to do the job. Anne-Marie Birch, 47, was strangled by her estranged husband of 25 years in a field near Broadstairs; afterwards, he returned the dogs she had been walking to their owners, cleaned himself up in an Asda lavatory, and then drank two pints at the bar of a pub before calmly telephoning the police to let them know what he had done. Assia Newton, 44, was strangled with a dog lead at home in Pencoed, Wales, by her husband of 20 years, a man so controlling he had installed an app on her mobile that enabled him to hear the name of everyone who called her.

Anne-Marie Birch, murdered age 47, with her daughter Molly. Photograph: BBC

The interviews Engle has gathered are remarkable, even by her standards. It has long been her belief that straight questions will be rewarded with straight answers, and so it proves here. The narratives she elicits are at once quotidian (“You were walking on egg shells… you never knew what mood he’d be in”) and horrifying (“Oh, will you just fucking die,” said Joanna Hall’s killer, as she lay on the floor beside him, gasping for breath). And then there is her attention to the aftermath: rather than let people try, and fail, to describe the endless magnitude of it, she has the pictures. She is there when Assia Newton’s husband, Kelvin, telephones his daughter Sophia from prison – thanks to her continuing relationship with her father, Sophia’s sisters, Sameera and Charmaine, no longer to speak to her – and she is there, too, when Sue takes Chantelle Barnsdale-Quean’s small daughters, Abigail and Isobel, to visit their mother’s grave. On the cemetery paths, heartbreakingly, they turn cartwheels.

“I don’t want to say that those girls are resilient,” says Engle. “But in the film, they represent resilience.” From the outset, Sue and Stuart were clear that they were happy for her to talk to the children, who live with them now, and once the BBC and the girls’ counsellors had given her the go-ahead, this is what she did. “Protecting them was paramount, but the other side of that is to give them a voice. I filmed them, and I chatted to them, but it wasn’t an interview. That would have been out of the question.” In their bedroom, where they are colouring in – they favour pink and purple, their mother’s favourite colours – they describe how much they miss Chantelle. What about their father? (Convicted of his wife’s murder, he is serving a minimum prison sentence of 18 years.) “I don’t miss him that much,” says Abigail, uncertainly. “I hate him,” says Isobel, more fiercely. Their grandparents told them only that “daddy had killed mummy”. It was left to a neighbour’s child to reveal how precisely he had done this.

It’s not for a journalist to prioritise her own feelings when it comes to a project like this one. But still, I wonder what effect making this film had on Engle. “It was quite a turbulent time for me,” she says. “When you’re working, you feel robust. You think you can cope with anything. But the horror did stay with me. One policeman showed me all the photos of a woman who’d died, and I’m still haunted by those. I wish I had not seen them. You feel very helpless. There’s nothing reassuring you can say. And sometimes, too, the detail of what people describe can resonate with things that have happened to you. We’ve all, whether at home or at work, experienced relationships where someone has bullied us, or been unkind, where we were not sure whether what was happening was OK, or not OK, where we should draw the line. One policeman said to me that abuse is on a continuum: it can be somebody making a cup of tea for themselves, and not for you. [Thinking about this] starts to make the world feel very unsafe. You have the sense that this is the tip of an iceberg.”

Kirsty Humphrey, murdered age 23. Photograph: Kirsty Humphrey/BBC

This anxiety – the things that go on behind closed doors – is something she suggests visually in the film, with its lingering images of net curtains, china ornaments and long suburban streets. “The landscapes are important. Such ordinary places, but cumulatively, they start to seem sinister. The women who die each year are only a tiny fraction of the number of those who are being abused.” In this shorthand, she catches, too, the curdled hope of a relationship gone wrong: a half-eaten ice-cream cone balanced on a low wall; a streak of red paint on a creosoted fence; a single white feather caught in the dark green branches of a garden shrub.

The women whose deaths her film relates came from different places and backgrounds, and were of all ages, young and old. Some had lived for decades with the man who killed them; others knew him barely at all. Nevertheless, as the hour ticks by, it becomes apparent that they did have at least one thing in common: reluctant to tell others what was going on, they spent too long feeling unable or unwilling to exit their relationships. “I told her to leave him,” says Molly, the teenage daughter of Anne-Marie Birch. “She said: I don’t know what he’d do if I did.” In the end, she tells Engle, her mother thought it easier just to keep going, to put his behaviour down to his being “weird”. By the time she did involve outsiders – the last time Molly saw her, she was on the telephone to the police – it was too late. As Lee Birch later insisted, no non-molestation order – or any other kind of legal intervention – was ever going to stop him.

Engle doesn’t believe one single policy decision could mitigate any of this. “I want all the agencies involved to be constantly reviewing their processes,” she says. “Some police forces are very good now, and some are not. Some were noticeably less helpful to us than others. Practice varies. There is undoubtedly room for improvement. But this is complex. What’s important to me is that, in our times, we worry about boys as well as girls, about men losing power and feeling emasculated – and that’s right. But it also means that the situation of women is obscured. It’s perhaps less visible, and that’s the point of the film. These things can’t be addressed if people don’t know what the issues are. If people think women are all powerful – well, this is the corrective. There is still a real asymmetry [between men and women] and here’s the evidence.” This is not to suggest, however, that the abusers in her film are always the more powerful. “They are controlling, but they may not have any real power. It might be the opposite. The women are the breadwinners, or quite strong; the men feel inadequate, or lack self-esteem. All I can say is that when documentary-making is at its best, it holds a mirror up. If anyone sees their own situation in here, perhaps it will help them to realise that it is bad, and that they might consider getting out of it.”

Engle has enjoyed a long and highly successful career at the BBC. She joined it in 1988 after Oxford and a brief period as a university lecturer, working first on The Late Show and then on her own films; her series Britart was commissioned for the launch of BBC4 in 2002. But it would be misguided to suggest that Love You to Death might mark her zenith. If the BBC continues to support her – having survived round after round of redundancies, she is the only 53-year-old female film-maker still on its staff – the best could be yet to come. She grins. “I think my craft is consistent, if that doesn’t sound arrogant. I feel I have the equipment now to take on anything. I am proud of this film, but I suppose what’s different about it is that its craft is more obvious to people. When my films are more full of wit and irony, as they’ve tended to be, that craft might be less noticeable.”

Is she ever asked to make changes to her singular films? She says not, though it is certainly true that her documentaries are now more likely to tell human interest stories than to explore, as they did in the past, social history. “The impetus [for that] has come from the industry. Budgets are tiny on BBC4 now, and if I want to go on making beautiful films, with money for archive, research and a camera crew, I must earn my right to be on a channel like BBC2, where budgets are bigger.” Festivals, it’s true, still privilege a certain kind of machismo in documentary-making, though this hasn’t stopped her being nominated for awards (last month, she received an outstanding contribution award at the Aldeburgh documentary festival). But in any case, that circuit is not really her world. Balancing family life – she has two sons – with her work as a director has meant she has never had much time for “schmoozing”. What will she do next? It’s unclear. At the moment, she is waiting for her next green light. In the meantime, though, there is Love You to Death, a film that manages to wrest some small piece of beauty and hope from the roughest of terrains. Intimate and unsparing, it deserves to win everything, not least an hour of your time.

Love You to Death: A Year of Domestic Violence will be screened on BBC2 on 16 December

A daughter’s story

Chloe Siokos, 80, died on 22 January, 2013. Her body and that of her former husband of 40 years, Argyrios, 69, were found in her flat in Finchley, north London, following a fire. He had hanged himself. She had been hit with a hammer, and her throat had been cut. Argyrios, who was supported financially by his wife, had a history of violent behaviour, and came to believe that his wife and stepdaughter, Annabella, a mental health practitioner, who tells her story below, were plotting to kill him. Diagnosed with cancer shortly before the murder, it is believed that he could not tolerate the idea that his wife would outlive him.

“My mother was a very kind, generous, considerate person, and she was bubbly, too. She had a dress factory; she used to make clothes for Twiggy. I think that’s how they met: he was living with one of the machinists. [When they got together] the whole family was against him. We didn’t feel he was honourable, or to be trusted. He didn’t have many friends. He was manipulative and dominating. We all told her it wasn’t right. I think she was determined to try to prove us wrong.

When her neighbour rang me in the morning to tell me the house was on fire, I knew straightaway he’d killed my mother

“The abuse started at the beginning of the marriage. He [temporarily] left her for an 18-year-old. He was a big man, and my mum was so delicate. She was afraid of him. I used to see marks on her, right until the end. He blacked her eye, but because she was by then older, the doctors missed the signs. They seemed to think it had just happened spontaneously. He was abusive and nasty, but if you tried to interfere, it had repercussions for my mother. To get properly away from him, I think she would have had to leave the country, just disappear.

“They separated in 2008. [By then] I felt that he was malevolent, that he had a disturbed mind. He was capable of anything. When her neighbour rang me at 6.30 in the morning to tell me the house was on fire, I knew straightaway he’d killed my mother. It had been obvious something wasn’t right. I had tried to tell her to be extra careful. But he was so strong.

“I can’t even begin to describe what it has been like. I think: could I have done something? But apart from kidnapping her, I can’t see what. She was a strong person. I can’t understand how she would let a man like that take over her life. He just exerted some kind of hold on her. This is going to take a long time to get over. I know I am in trauma. I keep getting flashbacks. I haven’t been able to properly grieve for my mother. It is so horrible.

“I think it’s very important that professionals step up on domestic violence. There is a lot of it out there. It’s vital that people get help. I know it’s difficult, that people feel embarrassed, unable to tell people. That’s why I took part in the film. I think we need more awareness. If it can help to save anybody, even one person, it will have been worth it.”