A teenager has told the court how he watched helplessly as his brother Kristy was drowned in a bath for being a witch.

Kristy’s younger brother, who cannot be named, described the killing in a five-hour video interview with police, part of which was played to jurors.

“Eric turned on the cold water and put it on him,’ he told officers the day after Kristy was found dead

“He told Kristy to get up but he wasn’t able to. I don’t know whether he could breath. He wanted to get up but he lay down in the bath and didn’t move again.”

Kristy remained motionless until Bikubi noticed he wasn’t breathing and attempted to perform heart massage, he added.

Kristy’s younger brother remained composed as his account of the beating leading up to the death was played to the court.

He said the violence had started after a pair of wet underpants were discovered in the kitchen of Magalie and Bikubi’s eighth floor flat.

Over the next few days Bikubi forced the youngsters to fast and hold all-night vigils during which they chanted the Lord’s Prayer, before he and Magalie turned on Kristy, jurors have heard.

Kristy was accused of being the “king” of the sorcerers, while sister Kelly, then aged 20, and another sister, who cannot be named, were said to be the “queens” and were also beaten.

“Eric took Kristy and started hitting him on his head with a metal bar and a big, cube-shaped stick,’ said his brother.

“Eric was sitting on the chair, he took the bar piece from some dumbbells and he was hitting Kristy on the head with it.

“His head was bleeding.

“He told me to go and get some tiles and open the bag,” he added. “He said to hit Kristy on the head like this and he hit him on the head.

“He said we would have to obey otherwise we would get hit. Then he picked up two tiles, then a third, then a fourth.

“When it was over he hit him with a stick. There was blood everywhere.”

At one point Bikubi managed to extract a witchcraft “confession” from Kristy, who admitted he was a “sorcerer” and “had a mission” to kill Bikubi and Magalie, the boy added.

He said Bikubi had called the children’s father, Pierre in Paris, to tell him they were witches and should be immediately collected before they were killed.

“I don’t know whether he thought it was a joke,” he told police.

“He said he was going to come on Monday.”