The birth of a new mum in childbirth was blamed on 'witchcraft sex' after rumours that she had slept with her brother-in-law.
Her family believe the woman, who lived in a tribe in the Congo's rainforest, was cursed after the unfaithful act.
Her brother-in-law, who is married to her sister, has now been accused of witchcraft and banned from seeing his two children.
Their story is told on Channel 4's new documentary Extreme Tribe: The Last Pygmies, which sees filmmaker Livia Simoka visit the Congolese Mbendjele BaYaka tribe.
She saw what life is like for the 250-member group, who live in mud huts and eat a diet of caterpillars and monkeys.
Tribe leaders Mama and Papa's daughter Akaya is married but the families did not get on after her sister died in childbirth.
Akaya says: "When we lost my sister I decided I would live at home - that I would stay and look after mum. But now my husband's mother wants him to find another woman."
The family accused Akaya husband Kengule of witchcraft, saying he used magic to kill her.
He said: "For a while my wife and I had a good marriage and then her family got upset with me.
"My wife's family accused me of sorcery. They say I killed my wife's sister.
"But when did they ever see me using sorcery?
"I barely see my children now. Akaya won't let me be with them.
"I don't know why everyone hates me so much. What have I done wrong?"
"I heard your family spreading rumours saying I had sex with your sister and that's why she died."
His mother also wanted him to find a new wife.
As the row continues to escalate the two families sit down to discuss what to do and decide that the marriage should end, leaving Akaya in tears.
The documentary also shows how women in the tribe have their teeth chiseled in official ceremonies to make them into sharp points.
- Extreme Tribe: The Last Pygmies is now on Channel 4 catch up.
