A teenage photography student was murdered by her father to silence her claims that he sexually abused her, a court heard.
Jurors were told both her parents then sent messages from her phone pretending to be her and saying she had run away to divert officers who were investigating her disappearance.
Bernadette Walker, 17, was last seen alive on July 18 last year when her father Scott Walker, 51, collected her in the car from his parents' house in Peterborough where she had stayed overnight, Cambridge Crown Court heard.
Lisa Wilding QC, opening the prosecution case, said Bernadette's body has not been found.
She said the girl's father and her 38-year-old mother Sarah Walker formed an 'unholy alliance', in a nine-minute phone call on July 18, to cover up her death.
Her mother did not report her missing to police until July 21, the prosecution say.
Ms Wilding said Bernadette, who wore glasses, had a habit of dying her hair in rainbow colours, was described by friends as 'something of a goth' and 'socially awkward', with many of her friendships online.
Bernadette Walker was killed by father Scott Walker (both pictured) after she accused him of sexual abuse, prosecutors have told Cambridge Crown Court where he stands trial for murder
Bernadette was last seen in July 2020 after staying at her grandparents' following her claims of sexual abuse against her father, until 'things calmed down a little' prosecutors told the court
She was also known as Bea.
Ms Wilding said that on July 16, Bernadette told her mother that her father 'had been sexually abusing her over a number of years'.
'Mother and daughter spoke about that allegation that night and into the following morning,' said Ms Wilding.
'Sarah Walker told Bernadette that she did not believe her.
'The following day, it was decided that Bernadette should go and spend the night with her paternal grandparents while things calmed down a little.'
Bernadette's father dropped her at her grandparents' house on the evening of July 17 and he collected her the following morning, prosecutors say.
'Since the day she disappeared she has not used or sought to access her telephone or social media accounts, she has had access to no money or banking and has not been seen at any hospital or other surgery,' said Ms Wilding.
'No-one who knew her or loved her has heard from her since that day.
Scott and 38-year-old Sarah Walker, both pictured, are accused of perverting the course of justice after prosecutors say they formed an 'unholy alliance' to cover up Bernadette's murder
'She is presumed dead and, as you will come to hear, it's likely that her body was disposed of, probably in the countryside in the hours that followed her killing.
'The prosecution allege that Scott Walker killed Bea to prevent her pursuing her allegations of sexual abuse any further.
'He then enlisted the help of her mother, his wife, to cover his tracks and to provide them both with some time to formulate the next part of their plan.
'In those hours and days in which they hid her disappearance from everyone and deliberately set a false trail, they achieved their goal.
'They diverted the investigation into her disappearance and death for sufficiently long and sufficiently well, that any hope of finding Bea's body disappeared with her.
'To this day, neither of them accepts that Bea is dead.'
An undated handout photo issued by Cambridgeshire Police of Bernadette. She was last seen in July in Peterborough. Her body has not been found, but police believe she has been killed
Ms Wilding said that Scott Walker collected Bernadette from his parents' home between 10am and 11am on July 18.
'When her grandparents said goodbye to Bernadette that morning, it was the last time that they, or anyone other than Scott Walker, saw her alive,' said Ms Wilding.
'At 11.23am on July 18 Scott Walker's telephone, which was usually in regular use, was off.
'It remained off until 12.54pm and the prosecution say that in that hour and a half he killed Bea.'
She said when his phone reconnected to the network at 12.54pm the first call he made was to Sarah Walker, which lasted for more than nine minutes.
'As you will come to see from all of the evidence, the only sensible conclusion that can be drawn from that telephone call is that Scott Walker told his wife that he had killed Bernadette and needed her help, immediately, to cover up Bea's disappearance and death, and to buy them both time to work out what should happen next,' said Ms Wilding.
Pictured: Cambridgeshire Police during the search for missing Bernadette in October last year. Cambridgeshire Police said the last searches took place near Etton in mid-December
'The story they concocted in that call, and which both relied on from that moment on, even until now, was that Scott had stopped the car on the short drive home to confront Bea about her allegations, that Bea jumped out of the car when he pulled over and that she ran off.
'Then, that Scott tried and failed to run after her and so returned home without her.
'From that moment on, Scott and Sarah Walker – Bea's own mother and father – were joined, the prosecution say, in an unholy alliance, designed and intended to mislead, to divert and to pervert the inevitable investigation into the disappearance and ultimately the death of Bea Walker.
'In the minutes, hours and days that followed, Scott and Sarah Walker hacked into Bea's social media accounts, sent false messages from her telephone which was still in their possession, pretending to be from her to her friends and family, and which were designed to lay a false trail to explain their subsequent failure to report her missing to the police.
'They lied to everyone around them … about her disappearance and they were unflinching in their pursuit of their devious, wicked plan.
'All parental love and responsibility was gone, if ever it actually existed.'
She said Bernadette's parents 'selfishly and ruthlessly … maintained their lying accounts which were designed to protect only themselves.'
Both were arrested more than six weeks later, Ms Wilding said.
Scott Walker denies Bernadette's murder on or after July 18 last year and four counts of perverting the course of justice.
Sarah Walker denies two counts of perverting the course of justice.
The trial continues.