Scott Walker, 51, was found guilty of killing 17-year-old Bernadette Walker, despite her body never being found.
It is still not known how Bernadette, known as Bea, died, but the last confirmed sighting of her alive was when Walker picked her up from his parents' home in Werrington, Peterborough, on July 18 last year.
Detective inspector Justine Jenkins, from the Beds, Cambs and Herts Major Crime Unit, said: “I am pleased we have been able to get justice for Bea after what has been such tragic circumstances. I just hope now we may get the answers we need to be able to find her and lay her to rest.
“If anyone has any information about this investigation which may help us find Bea, please get in touch.
“We may never know the truth about what Scott did and why, but we do know Bea had made allegations of abuse against him.
“My plea to anyone who may have been subjected to abuse is to speak to us. Bea thought she could confide in her own mother, who should have been able to protect her, but instead she met a tragic end.”
Before she went missing, Bernadette made allegations of sexual abuse against the person she knew as “dad”, although he was not her biological father.
She stayed with Walker's parents overnight and was picked up on the morning of Saturday July 18.
Walker did not take the teenager back to their home in Century Square, Millfield, that morning.
His mobile phone activated cell sites in the Dogsthorpe and Gunthorpe areas, both in the opposite direction, and at just before 11.30am it disconnected from the network and didn’t reconnect for an hour-and-a-half.
Over the next seven weeks, Walker and his former partner, Bernadette's mother Sarah, lay a trail to suggest Bea was still alive and had run away from home.
Walker claimed he had stopped the car on their way back from his parents’ home to speak about the allegations Bernadette had made when she got out and ran off in Skaters Way, leaving her rucksack behind.
Passwords on Bea’s social media accounts were changed and messages sent to friends and family to make it look as though Bea had simply run away from home.
Sarah Walker reported Bernadette missing to police on July 21.
During the investigation, police discovered that instead of going straight to collect her that morning, Scott had gone to a lock-up garage owned by his parents in Walton.
And it was not the only time he visited this location in the days after Bea was reported missing.
Once the phone reconnected to the network, after 90 minutes of being disconnected, the first call he made was to Sarah. It lasted nine minutes.
At trial, the prosecution argued that this call was when Scott Walker told Sarah Walker that he had killed Bernadette and needed her help.
Lisa Wilding QC, prosecuting, said: “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.
“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 48 hours following Bea's disappearance, both Scott and Sarah made multiple trips to the Walton lock-up as well as to Cowbit, a rural area of Lincolnshire, in the dead of night.
The allegations Bea had made about being sexually abused by her father were passed to police via a social worker on July 22.
On September 10, Scott was arrested for this and allegedly coercively controlling Sarah. The following day, the investigation became a murder enquiry.
Bea’s rucksack was found in the Walton lock-up and a diary found inside. An extract read: “Told my mum about my dad and the abuse. She called me a liar and threatened to kill me if I told the police. What kind of parent wouldn’t believe their daughter?”
Sarah Walker had previously admitted perverting the course of justice by sending messages from Bea’s phone and providing false information to police, but denies “knowing or believing” Bea was dead.
Police claim Sarah did know Bea was dead, which is still being deliberated by the jury.
No verdicts have been given for these charges yet and the jury have been told a majority verdict would be acceptable for those counts. This means that a verdict on which at least 10 jurors are agreed can be taken.
Bea’s whereabouts remain unknown, despite extensive searches by specially trained officers which continued for many weeks.
DI Jenkins said: “We know Bea was without her mobile phone when she left the family home on July 17.
“Despite this, a number of messages via text and social media were sent from Bea’s phone, by both Scott and Sarah, to make it look as though she was still alive and not wanting to go home. This would then explain their failure to report her missing for several days.
“After three days of Bea having been ‘missing’, Sarah contacted us via webchat to ask for advice and eventually called 101 to make a formal missing person report. It was clear nothing had been done to make sure Bea was safe, just a very long line of lies and deceit which grew by the day.”
Information about the support available for those who have suffered sexual abuse, along with how to report information, can be found on the force website.
Information about the investigation can be passed on to police either online at or by calling 101.
Both Scott and Sarah Walker will be sentenced at Cambridge Crown Court on a date which is yet to be confirmed.