On the night of 27 July 2023, Kimberly Milne jumped to her death from a road bridge.

Her suicide came after months of mental health crises, compounded by a campaign of domestic abuse at the hands of her former partner. In this regard, to the officers who attended the scene, Kimberly’s was a depressingly familiar story.

What those officers could not have known is that the tragedy that unfolded on that summer evening would take on a unique significance, culminating in a prosecution that, almost three years later, would make British legal history.

Kimberly’s estranged husband, Lee Milne, 40, was interviewed at a police station less than a mile from the scene shortly afterwards. It emerged that, in the minutes before she took her own life, he had followed Kimberly, 28, on to the bridge.

When Kimberly died, Milne was on bail accused of a catalogue of domestic abuse offences and banned from contacting her. However, numerous witnesses recalled seeing them together at a retail park in Dundee on the night of her death. They remembered Kimberly “cowering” as Milne shouted at her and trapped her against a wall. One witness said Kimberly looked “very distraught”.

CCTV footage showed Milne driving erratically while Kimberly was in his car, then remonstrating with her in a supermarket. About half an hour later, Kimberly climbed across the barrier of a bridge above the A90 road that links Dundee and Aberdeen. Milne told officers that he had run towards Kimberly because he wanted to stop her from jumping, but she had let go of the railings.

The Guardian has spent months studying the cases of women who take their own lives after prolonged abuse in intimate relationships. Analysis by academics suggests that victims of domestic abuse are now more likely die by suicide than be killed by a partner. In the vast majority of these cases, alleged abusers are not investigated for their role in a partner’s suicide. In some cases, existing domestic abuse investigations have been closed without explanation shortly after the alleged victim’s death.

However, in Kimberly’s case, prosecutors sought to answer a “complex question”.

Led by Laura Buchan, the legal director at Scotland’s Crown Office and Procurator Fiscal Service, the prosecution posited: “Can a partner be held criminally responsible for the death of a victim who has taken their own life following a course of domestic abuse?”

The trial that followed marked a significant legal milestone: Milne was found guilty of culpable homicide and engaging in abusive conduct. He is the first person anywhere in Britain to have been convicted by a jury of killing a former partner after prolonged domestic abuse, despite not physically causing her death.

On Friday, at the high court in Glasgow, Kimberly’s family cried and embraced in the public gallery as Milne was jailed for eight years. Sentencing him, the judge, Lady Drummond, said that she could do nothing to bring Kimberly back, or ease the grief of her devastated loved ones. “By the jury’s verdict, you must bear responsibility not only for all of your abusive acts but for causing her death,” she told Milne.

Kimberly grew up in a close-knit family in Dundee – her mother and sisters described her as “one in a million” in victim impact statements provided to the court – but her life was blighted by mental health problems. She once predicted that she would not live beyond the age of 21.

As a child, she was sectioned several times. She was diagnosed with a personality disorder, and, at times, she tried to numb the pain with illegal drugs. “Kimberly wanted to be normal like everybody else,” her mother, Lynne Bruce, told Milne’s trial. “She couldn’t understand why she wasn’t.”

Bruce described her daughter as being “liked a coiled spring”. “Sometimes she used to self-medicate,” she said. “Kimberly never had a nice life, she was in periods of turmoil.”

In 2020, Kimberly survived a suicide attempt. The next year, she met Milne online. According to her younger sister, Nicky Bruce, he presented as a “knight in shining armour”.

“She just wanted to be loved,” Nicky told the court. At first, the relationship appeared to be going well, and the couple became engaged. But soon, cracks began to show.

The jury accepted that Milne had become abusive towards Kimberly before they married in October 2022. In the months before the wedding, he shouted and swore at her, called her derogatory names and attacked her several times. On one occasion, he prevented her from leaving his flat.

“I don’t think Kim wanted to be married,” Nicky said. “I think he just filled her head with absolute gobbledegook. I think he made her feel like the family didn’t love her.”

In evidence, Kimberly’s older sister, Lynsey Anderson, recalled that, the day after the wedding, Kimberly was “in a mess” after a fight with Milne. Anderson said she called a taxi to take Kimberly to their grandmother’s house. “He’d put her out. She was hyperventilating, crying and asking me to get her home.”

Anderson told the court that she saw bruises on Kimberly’s neck and arm during the relationship and, on one occasion, she noticed a bite mark. “You could see the teeth,” she said. “It was like an indentation in an apple when you take a bite out of it.”

Morgan Wilson, a community mental health nurse, noted that Kimberly described Milne as a “manipulator” who tried to “make her feel she is losing her mind”. The court heard that, in February 2023, during a period of separation, he sent Kimberly “an image of himself with a needle in his neck” saying “she would be responsible for his death”.

Kimberly made several attempts to end the relationship, but told her family Milne would repeatedly threaten suicide. “How can I leave him if he’s saying he’s gonna do himself in without me?” she said in one message. In another series of texts, sent to Milne, she said: “You berated me last night and choked me until I was nearly unconscious … You really don’t care, do you? This is over.” Milne replied: “I am ashamed you don’t deserve that. I’m sorry.”

In May 2023, Kimberly received inpatient treatment at the Carseview Centre, an NHS mental health facility in Dundee, after a suicide attempt. She told staff she had suffered physical abuse and “mental torture” at Milne’s hands for almost two years. She agreed to make a statement to police and described in detail the abuse she had suffered from early on in the relationship until her admission to hospital. This included an incident where she barricaded the living room door with a table after Milne choked her. She said Milne had forced entry and continued to attack her.

“Lee repeatedly punched my ribs and I was begging him not to hurt me but he was not listening,” she said. “I felt unsafe so I decided not to leave that night. I slept with a knife under my pillow as I was so frightened of him.”

Milne appeared at Dundee sheriff court later that month, in connection with domestic abuse offences. He was granted bail on the condition he did not approach or attempt to contact Kimberly. He repeatedly violated these restrictions and, in the week before her death, threatened her while brandishing a pole.

When Milne left the police station on the morning of 28 July, he decided to break the news of Kimberly’s death to her mother. Lynne Bruce was woken by his knock at her door.

“When I answered, he said something along the lines of: ‘Kim has gone’,” Bruce recalled in a police statement. “I didn’t know what he was on about and he came in the house … He then said Kim had gone up to the bridge and he had chased her. He tried to grab her hands and she looked up at him, shook her head before jumping off.” Bruce said she was devastated by her daughter’s death.

Police initially treated Kimberly’s death as unexplained, and sought to track down witnesses who had seen the former couple in the hours beforehand. As a fuller picture emerged, the prospect of charging Milne with culpable homicide was discussed. Scotland has a different legal system to England and Wales, and the offence of culpable homicide is similar to manslaughter.

Alex Prentice KC, a leading criminal lawyer who went on to prosecute the case, was asked to advise officers on whether Milne could be charged with killing Kimberly, although no one had ever been convicted of culpable homicide in Scotland after a domestic abuse related suicide.

There was arguably just one comparable case anywhere in the UK. In 2017, at Stafford crown court, the stalker Nicholas Allen admitted the manslaughter of his former partner, Justene Reece, who killed herself after a six-month campaign of threats and harassment. However, at the time of Kimberly’s death, no jury anywhere in Britain had reached a guilty verdict in a case of this nature.

Prentice said that there were initially mixed views on whether the available evidence would support a culpable homicide charge. He told officers they would have to find evidence of a “causal connection” between the domestic abuse and Kimberly’s death.

“I looked at it and, at the early stage, my view was it needed more work done, but I could not say that a causal connection could not be made,” Prentice said. “If we could establish this course of continual abusive behaviour to the extent that Kimberly felt that there was nowhere to go, and that the only way out was to take her own life, it seemed to me possible that a culpable homicide charge could be brought. Further work was done by the police on my instruction.”

Milne was charged with culpable homicide and domestic abuse offences in September 2023. While awaiting trial, he sexually assaulted two primary school aged boys. He was sentenced to a three-year supervision order and placed on the sex offender register after a three-day trial at Forfar sheriff court in Angus. This conviction was revealed by the local newspaper, the Courier, after he was found guilty of killing Kimberly.

Milne chose not to give evidence in his own defence during his trial, which began in February at the high court in Glasgow. His defence counsel, Mark Stewart KC, argued that Kimberly’s longstanding mental health issues had played a central role in her decision to jump to her death.

However, in his closing speech, prosecutor Prentice asked jurors to consider the impact of prolonged domestic abuse on Kimberly’s already fragile state of mind.

“People sometimes make assumptions about domestic abuse and the circumstances in which it happens,” he said. “You must set such assumptions to one side. It might be counterintuitive to think, if Kimberly Milne was really, truly unhappy this marriage, why didn’t she just leave? Well, where was she going to go? It’s not always possible to just leave.”

Milne was found guilty of culpable homicide and domestic abuse on 2 March and remanded in custody to await sentence. Kimberly’s family’s relief at the verdict was laced with anger. Lynsey Anderson, Kimberly’s older sister, told journalists: “He is a monster lurking in the dark waiting for his next victim. We know now he won’t be able to victimise anyone else.”

However, when Milne returned to the court for sentencing on Friday, Lady Drummond said he had failed to fully appreciate the gravity of his actions. Drummond said a custodial sentence was the “only appropriate disposal”.

“Following your actions, Kimberly Milne reached a point of despair, such that she climbed over the barrier of a road bridge and fell to her death,” she said. Milne showed no emotion as he was led from the dock.

Almost 80 miles away, in Dundee, the bridge over the section of road where Kimberly died remains a memorial to her. Fixed to the railings are purple ribbons and bouquets of flowers, some in personalised vases from family members. Drummond, the judge, acknowledged their pain: “They are devastated by her death. Nothing I can say or do today will bring her back or ease their grief.”

Staff at the local branch of Women’s Aid said they hoped Milne’s conviction would help raise awareness so other domestic abuse cases would be taken more seriously.

For Prentice, the breakthrough is a moment which could cause prosecutors to rethink their approach to domestic abuse-linked suicides.

He said that prosecutors in Scotland would look “very closely” at similar cases in light of the verdict. “I don’t have the impression this will open floodgates because they are difficult cases and we have to justify bringing an indictment on the evidence and with a careful analysis,” he said. “But it’s been done now, so that means in suitable cases, it will be done again.”