A father murdered his daughter after she accused him of sexual abuse and then formed an "unholy alliance" with his wife to cover up the crime, a court has heard.

Bernadette Walker, 17, was last seen alive on July 18, when her father, Scott Walker, 51, collected her from her grandparents house where she had spent the night.

The previous day the photography student had told her mother, Sarah Walker, 38, that she had suffered years of sexual abuse at the hands of her father.

But Cambridge Crown Court heard that she did not believe Bernadette – also known as Bea – and suggested she go and stay with her grandparents in order to let things calm down.

It is alleged that after collecting her in his car Mr Walker then killed his daughter before disposing of her body which has never been found.

After telling his wife what he had done, it is claimed the couple then conspired to cover up the crime by sending messages from Bea’s phone purporting to be from her claiming she had run away.

They waited three days before reporting their daughter’s disappearance to the police.

Ms Wilding told the jury: "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."

Bernadette Walker was last seen alive on July 18 

The jury was told that it was on July 16 last year that Bea, who was socially awkward, had confided in her mother that her father had subjected her to years of sexual abuse.

Ms Wilding explained: "Mother and daughter spoke about that allegation that night and into the following morning. 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."

The court heard that Mr Walker had collected his daughter between 10am and 11am on July 18.

Between 11.23am and 12.54pm his mobile phone, which was usually in use, was switched off.

The prosecution alleged that it was during that period that he killed his daughter.

When his phone reconnected he made a phone call to Mrs Walker that lasted for nine minutes, Ms Wilding explained.

"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 added.

"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."

The couple were arrested six weeks after Bea’s disappearance.

Mr Walker denies murder and four counts of perverting the course of justice while his wife denies two counts of perverting the course of justice.

The trial continues.