The sister accused of murdering her brother Kristy Bamu in a "prolonged attack of unspeakable savagery and brutality" had accused a young girl of sorcery two years before, a court heard on Friday.
Magalie Bamu and her partner Eric Bikubi accused Naomi Ilonga, 19, of being a witch and made her cut her long hair to "release the witchcraft", jurors at the Old Bailey heard.
The prosecution says Kristy and his two brothers and two sisters were beaten and terrorised for four days at the flat in Forest Gate, east London.
They had been accused of being witches and sorcerers after arriving from their home in Paris to spend the festive season with the family.
Kristy, his sister Kelly, 20, and an 11-year-old sister were accused of influencing another child in the family.
Jurors heard Kristy was tortured with "an armoury of weapons" and had 101 injuries before being placed in the bath of water where he "begged to die".
Brian Altman, QC, prosecuting, said family friend Naomi stayed with the couple for a month in August 2008.
He said: "Bikubi accused Naomi of having got witchcraft because she would bite her nails.
"He was concerned about her sleeping pattern and accused her of disturbing (the child's) sleep.
"He told Magalie Bamu to throw anything away that Naomi had touched, including articles of clothing and pots, pans and plates, which Magalie did.
"Bikubi did not allow them to eat for three days and told Naomi to pray. He prayed to release Naomi's 'spiritual soul'.
"They stayed and slept together in the living room for the three days but prayed all night and slept little.
"Naomi had to consent to the cutting of her hair, which was long and of which she was so proud, to release the witchcraft."
The teenager had also been grabbed her and slapped her hard on the back, it was alleged.
Bikubi has pleaded guilty to Kristy's manslaughter on the grounds of diminished responsibility, but this is rejected by the prosecution. He has admitted assaulting Kristy's sisters.
Bamu denies all the charges, but Mr Altman said she had taken part in the abuse and had been "stoking the fire of violence".
The trial was adjourned to Monday.