A Russian mistress stabbed her married lover and his wife to death and then drowned two of their young children, police say.
Ruzanna Shvarts stabbed to death Russian economist Vladislav Saaya and his wife Lilia, both 35, according to her confession.
The 25-year-old also drowned girls Darimaa, six, and Aisel, four, in their bath, say prosecutors.
She is accused of setting ablaze the family flat in Ak-Dovurak in the southern Tuva region of Russia to cover-up the murders.
Police are investigating whether Shvarts' 19-year-old sister Melina was also involved after being implicated by her sibling.
The dead couple's eldest child, daughter Aiza, 12, was not home at the time and has been orphaned by the tragedy.
A police source cited by The Siberian Times said: 'Ruzanna was Vladislav's lover, and she came to visit him with her sister.
'They drank alcohol. Suddenly Vladislav's wife Lilia came back home with the children. She started to argue with Ruzanna and this turned into a fight.
'Melina insists that at this moment she left the flat. And when she came back, it turned that her sister had stabbed Vladislav and Lilia and killed their kids.'
An anonymous friend of the family's said she was said she was astonished that the respected family man had a lover.
Shvarts is accused of setting ablaze the family flat in Ak-Dovurak in the southern Tuva region of Russia to cover-up the murders
Gruesome pictures show the scene of the tragedy in Ak-Dovurak in the southern Tuva region of Russia
'He graduated from university and worked as an economist,' she said.
'His wife was an accountant, and worked as the head of storehouse. I still cannot understand how this could happen.
'Our town is very small, everyone is talking about this tragedy, this horror. He was an exemplary family man, not one of those who would have the affairs on the side. He hardly drank.'
A local woman said that the mistress was 'a beautiful girl, very bright' from a 'good' family, and that she had a three year old son. It is not known if the man she is accused of killing was the child's father.
'The younger one is married and has two kids already,' she said.
The local governor Sholban Kara-ool expressed horror over the murders, and called for children to be protected from 'adult madness'
'I am shocked that they are capable of this. They are mothers themselves, how could they kill children?'
The local governor Sholban Kara-ool expressed horror over the murders, and called for children to be protected from 'adult madness'.
Ordering a day of mourning he said: 'I have a lump in my throat. I'm so sorry for the children, brutally murdered in their own home.
'I'm so sorry for the young mother, who was guarding the family's well-being. What a pity that the head of the family failed to save himself and his loved ones. All Tuva mourns these innocent children.'
He said: 'It is necessary to think more deeply about what caused such a bloody accident. And how we can protect children from adult madness.'