Eric Bikubi, 28, and his partner Magalie Bamu, aged 29, have been convicted at the Old Bailey of killing Kristy Bamu after accusing him of being a sorcerer who practised witchcraft.
The couple, who live in Newham, acted after accusing Kristy of controlling and adversely influencing a young boy, the jury was told.
They originally came from the Democratic Republic of Congo, where witchcraft is called Kindoki, and exorcisms are carried out in some churches.
In 2010, Unicef reported 20,000 children accused of witchcraft were living on the streets of DR Congo's capital Kinshasa.
In the DR Congo, accusing a child of being possessed is a criminal offence, a law that has been in place for several years.
But in 2008 I travelled to Kinshasa to see if it was making any difference and, at that time, the answer was not at all.
Which is why I found myself in one of the city's slums late at night knocking on the door of tin-roofed shack that doubled as a church.
Pastor Tsimba let me in and showed me three children who he had diagnosed as having Kindoki.
The youngest was probably six, the oldest no more than 12. They had been in the church for days, deprived of food and forced to work. Their parents were paying for the privilege.
The only light came from flickering candles and storm lamps. The pastor began to shout and pray.
One by one he brought the children up to the front of the church. He ordered them to lie down and, still shouting and chanting, began slapping their stomachs, one, two, three times. Each harder than the last.
Then he took a candle and poured burning hot wax on them, leaving them grimacing and squirming but making almost no sound. Their eyes were wide and staring.
Finally, as a bizarre conclusion to the ritual, Pastor Tsimba produced a length of pipe and held it hard against their belly buttons.
One after another, he made a play of sucking hard on the pipe and in triumph then spat a lump of meat he claimed to have sucked out of them into a bowl.
The meat he claimed had been been fed to them by a witch, infecting them with Kindoki. The children, bewildered and quiet, were now in his words "delivered".
I alerted a social worker to the plight of the children. An extraordinary and dedicated man, he said he would do all he could to help them.
But his unit had not paid him for months, there was no money for petrol or even a bus fare. So he did his work on foot.
He walked miles each day, visiting as many churches as he could, in this sprawling city of nine million people.
An "obsession" with witchcraft and sorcery led a couple to brutally murder a 15-year-old boy at a flat in east London.