In July 2018 three teenage sisters stabbed and battered their father to death in his sleep, in their Moscow flat.
Investigators have confirmed the girls' father abused them physically and psychologically for years.
Charged with murder, the sisters and what should happen to them have become one of the hottest topics of debate in Russia and more than 300,000 people have signed a petition calling for their release.
What happened to the father?
On the evening of 27 July 2018 Mikhail Khachaturyan, 57, summoned Krestina, Angelina and Maria, who was a minor at the time, one by one to his room. He scolded them for not cleaning the flat properly and sprayed pepper gas in their faces.
Soon afterwards, when he had fallen asleep, the girls attacked him with a knife, hammer and pepper spray, inflicting fatal wounds to his head, neck and chest. He was found to have more than 30 knife wounds.
The young women then called the police and were arrested at the scene.
The investigation soon uncovered an extensive history of violence in the family. Khachaturyan had regularly beaten his daughters over three years, torturing them, keeping them as prisoners and sexually abusing them.
That evidence against their father is cited in their indictments.
Spotlight on domestic abuse
The case quickly became a cause celebre in Russia. Human rights activists argued that the sisters were not criminals but victims, as they had no means of getting help and protection from their abusive father.
However, there are no laws protecting victims of domestic violence in Russia.
Under legal changes introduced in 2017, a first-time offender who beats a family member, but not badly enough to put them in hospital, will face only a fine or up to two weeks in custody.
Police in Russia usually treat domestic abuse as a "family issue", providing little or no help at all.
The sisters' mother, who had also suffered beatings and abuse from Khachaturyan in the past, had approached the police years before. So did the family's neighbours, who were highly afraid of him. But there is no evidence that the police acted on any of these appeals for help.
At the time of the murder the girls' mother was not living with them and Khachaturyan had forbidden his daughters from contacting her.
According to psychiatric assessments, the girls lived in isolation and had been suffering from post-traumatic stress (PTSD).
What has happened during the investigation?
The Khachaturyan sisters' case has moved slowly. They are no longer in custody, but they are subject to restrictions: they cannot speak to journalists, nor to each other.
Prosecutors insist the killing of Khachaturyan was premeditated murder, as he was asleep and the sisters co-ordinated their actions, snatching the knife earlier that morning. The motive was revenge, they argue.
If found guilty under that charge the sisters face up to 20 years in jail. It is alleged that Angelina wielded the hammer, Maria the hunting knife and Krestina the pepper spray.
However, the sisters' lawyers say the killing was in fact an act of self-defence. Indeed, the Russian criminal code allows self-defence not only in cases of immediate aggression, but also in cases of "continuous crime", such as a hostage situation where the victim is being tortured.
The defence insists that the sisters were victims of "continuous crime" and should therefore be released. The sisters' lawyers are hopeful the case could be dropped, as the investigation has confirmed extensive abuse by Khachaturyan towards his daughters dating back as early as 2014.
Human rights activists and many other Russians now want the law changed and measures introduced such as state-funded shelters, restraining orders and courses for managing abusers' aggressive behaviour.
How widespread is domestic abuse?
There is no hard data on how many women suffer from domestic violence in Russia, only estimates, but according to human rights activists it could involve as many as one in every four families.
A number of other shocking cases have made headlines, including that of Margarita Gracheva, whose husband cut off her hands with an axe out of jealousy.
Some experts say that up to 80% of women held in Russian prisons for murder killed a domestic abuser in self-defence.
There has been something of a backlash against the Khachaturyan sisters among more conservative parts of Russian society. An association called Men's State, which cites "patriarchy" and "nationalism" as its two main values, and boasts almost 150,000 members on social media, organised a campaign called "Murderers behind Bars", insisting that the sisters should not be released.
In addition to a change.org petition calling for the sisters' case to be dropped, there have been solidarity poetry readings, rallies and theatre performances.
Daria Serenko, a feminist and activist from Moscow who helped organise a three-day support rally in June, says the main goal of the public events is to keep the story in the news and give everyone a chance to speak out safely.
"Domestic abuse is a reality of life in Russia. We can ignore it, but it affects our lives even if we have never had to experience it personally," she says.