A couple were convicted of murdering a 15-year-old boy who was tortured and drowned for being a witch in the UK.

Kristy Bamu, 15, was killed by his sister Magalie, 29, and her partner Eric Bikubi, 28.

He died in a bath at their tower block flat in Newham, east London, on Christmas Day 2010 after days of being abused.

He had come to London from Paris with his two brothers and two sisters to spend the festive season with Magalie.

But things turned sour when the couple, who were said to be obsessed with witchcraft known as kindoki in their native Democratic Republic of Congo, accused him of putting spells on a younger child.

Football coach Bikubi and Magalie were found guilty of murder at the Old Bailey and will be sentenced on Monday.

Judge David Paget told the jury of seven women and five men that the case was so "harrowing" he was exempting them from jury service for the rest of their lives.

"It is a case we will all remember," he told them. "Court staff will speak to you and offer help to you."

Kristy's family was not in London for the verdicts but a statement was read from his father, Pierre.

He said: "Kristy died in unimaginable circumstances at the hands of people he loved and trusted - people we all loved and trusted.

"I feel betrayed. How could they accuse, judge and sentence?

"To know that Kristy's own sister, Magalie, did nothing to save him makes the pain that much worse."

Detectives said other children in Britain had been subjected to terrible ordeals after being accused of witchcraft.

The court heard that Kristy was in such pain after three days of fasting and being attacked that he "begged to die" before slipping under the water.

He had been struck with knives, sticks, metal bars, and a hammer and a chisel.

After he refused to admit to sorcery and witchcraft, his punishments in a "deliverance" ceremony became more horrendous.

Bikubi forced them to pray for deliverance for three days and nights and deprived them of food and water.

The sisters, aged 20 and 11, were beaten along with Kristy, but escaped further attacks after "confessing" to being witches.

Kristy was singled out after wetting his pants. He was struck in the mouth with a heavy bar and hammer, knocking out his teeth.

Ceramic floor tiles and bottles were smashed on his head and a pair of pliers used to twist his ear.

The terrified siblings, who also included a 13-year-old boy and an autistic brother aged 22, were made to join in the torture.

At one point, Bikubi told the youngsters to jump out of the window to see if they could fly, the court heard.

They looked to their older sister to save them, but instead Magalie encouraged Bikubi and beat Kristy until he also confessed to witchcraft.

Sister Kelly, now 21, broke down several times in court as she relived the terror.

She said: "It was as if they were obsessed by witchcraft and then it became absolutely unbearable.

"I did not know what was going on in their minds. They decided we had come there to kill them."

Kelly added: "Kristy asked for forgiveness. He asked again and again.

"Magalie did absolutely nothing. She didn't give a damn. She said we deserved it.

"I am sure she still believes even to this day that we are witches."

At the end of their ordeal, the brothers and sisters were all placed in the bath to be hosed down in cold water with a shower head.

Brian Altman QC, prosecuting, said: "It was only when he realised that Kristy was not moving that Eric Bikubi stopped what he was doing and pulled him from the water. By then it was too late."

Kristy had 130 separate injuries and died from a combination of being beaten and drowning.

Mr Altman said: "In a staggering act of depravity and cruelty, they both forced the others to take part in the assaults upon

"As Kristy's injuries became ever more severe, he even pleaded to be allowed to die.

"Eventually Bikubi took him into the bathroom, put him in the bath and started to run the water.

"Kristy was just too badly injured and exhausted to resist or to keep his head above the water.

"Kristy was killed in the name of witchcraft. It is hard to believe in this day and age anyone can believe someone was practising witchcraft."

The jury was told that in the DRC, witchcraft was practised in Christian churches but could become "evil" when out of the church's control.