Teenagers must serve at least 20 years for murders of mother and her daughter
A teenage couple believed to be Britain's youngest double-murderers have been detained for at least 20 years for the brutal "executions" of a mother and her daughter.
The boy and girl - both 14 at the time of the murders - had sex, shared a bath and watched four Twilight vampire films as they "revelled" after the stabbing of dinner lady Elizabeth Edwards, 49, and 13-year-old Katie Edwards.
Both killers stared straight ahead as they were handed life sentences by Mr Justice Haddon-Cave, who said the pair had a "toxic" relationship and acted in a "grotesque" way.
The male defendant, wearing a dark blue jumper and dark trousers, slouched in his seat in the dock as he was sentenced, briefly pursing his lip and glancing towards a security guard as he was sentenced.
The court was told the boy, who admitted murder, used a kitchen knife to stab both victims in the neck after attacking them as they slept at their home in Spalding, Lincolnshire, in April.
His girlfriend, who helped to plan the "cold, calculated and callous" killings, denied murder, claiming to be suffering an abnormality of mental function which impaired her ability to form rational judgments, but was found guilty after a five-day trial.
Sentencing the pair, who are both now 15 and cannot be named for legal reasons, Mr Justice Haddon-Cave told Nottingham Crown Court: "This case is, in many respects, without parallel.
"The killings were brutal in the form of executions and both victims, particularly Elizabeth Edwards, must have suffered terribly in the last minutes of their lives.
"You were in it together from the beginning, you conceived of the killings together and planned it together.
"Both of you are perfectly intelligent and knew exactly what you were doing - either of you could have backed out at any time but you were selfishly determined to do it together.
"You then revelled in what you achieved. I see no reason to distinguish between you in any way."
Elizabeth Edwards' partner attending the hearing in a packed courtroom, along with Katie's father.
In a victim impact statement read to the court, Ms Edwards' eldest daughter Mary Cottingham, who was not present in court, spoke of her heartbreak.
She said: "I cannot believe what has happened. I have been thrust into the biggest nightmare of my life.
"To be told that my mum and sister had died was bad enough but to find they had been the victims of a murder is just unbelievable."
Addressing the couple - who had been likened to Bonnie and Clyde - the judge said: "There was remarkable premeditation and planning - it was, on any view, substantial, meticulous and repeated."
The judge stressed that neither teenager will be freed until they have served their minimum term, when they will be 35, and the Parole Board approves their release.
Offering mitigation before sentencing, defence QC Simon Myerson, representing the boy, said: "The reason these offences were committed was, as far as anyone can ascertain, the two children became trapped in a fantasy of their own devising.
"It's inconceivable that had they been fully mature, had they not been subject of their own personality disorders, that these offences would have been committed by them."
Andrew Stubbs QC, representing the girl, said the couple were in a "toxic relationship" and were "almost playing chicken" as they spurred each other on.
Speaking outside court, Karen Thompson, deputy chief crown prosecutor at CPS East Midlands, said: "This is one of the most distressing and disturbing cases that I have ever encountered."
Detective Chief Inspector Martin Holvey said: "The planning that went into the brutal murders of Elizabeth and Katie as they slept in their beds was cold, ruthless and chilling, as was the lack of remorse shown by the two juveniles afterwards."