A woman made no attempt to stop her boyfriend torturing and killing her teenage brother over claims he was a witch, a court heard today.
Kelly Bamu, 21, told a jury at the Old Bailey that her sister Magalie had failed to act when their younger brother was subject to a horrific ordeal.
Kristy Bamu, 15, was attacked with objects including a hammer and a pair of pliers before drowning in a bathtub.
Eric Bikubi and Magalie Bamu, both 28, are on trial for his murder, which they deny.
Today Philippa McAtasney QC, for Bamu, told the court that Bamu was as "powerless" as her siblings to stop Bikubi.
She asked Kelly: "You're upset because as you see it she failed to protect your brother, but she was as powerless as you all were, wasn't she, in fairness?"
The witness replied: "Really, she was powerless? No." She went on: "She could have stopped it and she didn't."
Bikubi has admitted manslaughter on the grounds of diminished responsibility, and to causing actual bodily harm to Kelly and another sister who cannot be named.
Magalie Bamu denies murder and causing actual bodily harm to her sisters.
Kelly told the court: "She could have said to Eric 'Stop, stop that's enough now' and he would have stopped."
Ms McAtasney said: "Nonsense, that is nonsense. That man had completely lost it, hadn't he?"
"He was aware of what he was doing," she replied. "There was all the blood around, he could see that blood around. He was aware of what was happening, now he says he was suffering from insanity. He knew what he was doing."
Kelly told the jury that Bamu and Bikubi were "in it together".
Her brother was found drowned in a bath at the couple's flat in Forest Gate, east London, on Christmas Day 2010, after allegedly being tortured when he was accused of witchcraft by Magalie and Bikubi.
The trial was adjourned until tomorrow.Suggest a correction