A couple have been found guilty of murdering a teenager they had accused of using witchcraft. Eric Bikubi, 28, and Magalie Bamu, aged 29, from Newham, east London, had denied killing Bamu's 15-year-old brother Kristy. Kristy drowned in a bath on Christmas Day in 2010, during torture to produce exorcism, an Old Bailey jury heard. Bikubi had admitted manslaughter on the grounds of diminished responsibility, but the prosecution rejected his plea. The pair, who are both originally from the Democratic Republic of Congo, were remanded in custody and are due to be sentenced on Monday. 'No comfort' The family of the murdered teenager said they had "forgiven" his killers. A family statement, read out in court by prosecutor Brian Altman QC, said: "We will never forget, but to put our lives back into sync we must forgive. "We take no comfort in the verdicts - we have been robbed of a beloved son, a daughter, a son-in-law. "Kristy died in unimaginable circumstances at the hands of people who he loved and trusted. People who we all loved and trusted." Judge David Paget, who was presiding over his last trial before retiring, told the jury of seven women and five men the case was so "harrowing" he was exempting them from jury service for the rest of their lives. 'Begged to die' "It is a case we will all remember," he told them. "Court staff will speak to you and offer help to you." During the trial, jurors heard Kristy was in such pain after three days of attacks by Bikubi and Bamu, who used knives, sticks, metal bars and a hammer and chisel, that he "begged to die", before slipping under the water. Kristy had been killed while he and his siblings were visiting Bikubi and Bamu for Christmas, the court was told. During the stay, Bikubi turned on them, accusing them of bringing "kindoki" - or witchcraft - into his home. He then beat all three of them and forced other children to join in with the attacks, the jury heard. But it was Kristy who became the focus of the defendant's attention, the prosecution said. Bamu and football coach Bikubi believed he had cast spells on another child in the family, the Old Bailey heard. Kristy had refused to admit to sorcery and witchcraft and his punishments, in a "deliverance" ceremony, became more horrendous until he admitted to being a sorcerer. The defence had argued Bikubi was mentally ill when he carried out the killing, with a scan of his brain showing lesions which "probably contributed to an abnormal mental state". 'Unimaginable violence' However, the prosecution had rejected this as a plea to reduce the charge against him. During her defence, Magalie Bamu told the jury Bikubi had forced her to join in the attack on the children. But the court heard there was ample evidence to show she hit Kristy and "stoked the fire of violence" Bikubi had embarked on in the flat. Outside court, chief crown prosecutor Jenny Hopkins said Bikubi "knew exactly what he was doing". "His actions were nothing short of torture and he inflicted on the victims violence on an unimaginable scale," she said. "It has also been proven that his accomplice - Magalie Bamu - acted of her own accord. "She willingly subjected her 15-year-old brother to extreme violence." Met Det Supt Terry Sharpe said: "Child abuse in any form, including that based on a belief in witchcraft or spirit possession, is a horrific crime which is condemned by people of all cultures, communities and faith, and is never acceptable in any circumstances." Kristy's family said they hoped comfort could be drawn from his death through raising awareness "of the plight of children accused of witchcraft or spirit possession and promote the need to safeguard children's rights".