Teenage lovers who are believed to be Britain's youngest double-murderers have each been locked up for at least 20 years after killing a mother and daughter.
The boy and girl - both 14 at the time of the murders - planned the killings of 49-year-old Elizabeth Edwards and 13-year-old Katie, who were stabbed through the throat and smothered as they slept.
The teenagers, now 15, went on to share a bath, have sex, and watch four Twilight vampire films after the murders in Spalding, Lincolnshire, last April, Nottingham Crown Court heard.
Sentencing the pair, who cannot be named for legal reasons, to life with 20-year minimum terms, Mr Justice Haddon-Cave said: "This case is, in many respects, without parallel."
The judge said the case had "defining and particularly chilling" features, including the young age of the defendants and that the offence was carefully planned.
As both teenagers remained composed in the dock, flanked by security guards, the judge condemned their conduct after the killings as "grotesque".
He told the teenagers: "This is a case of double murder. One of the victims was a young girl. There is a clear intention to kill both victims - both defendants admitted wanting to murder them.
"There was remarkable premeditation and planning - it was, on any view, substantial, meticulous and repeated.
"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."
The couple - who the court heard had a Bonnie and Clyde-style relationship - carried out the "cold, calculated and callous" attack which saw the two victims stabbed a total of 10 times.
Both the boy and the girl pleaded guilty to manslaughter but not guilty to murder at a hearing in September, with the male defendant admitting murder before the trial began.
His girlfriend maintained her innocence to 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.
During his sentencing remarks, the judge said both teenagers were equally responsible for the murders.
"This was an entirely joint offence," he told them. "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 had then revelled in what you achieved. I see no reason to distinguish between you in any way."
The judge went on: "I have carefully read the victim impact statements in this case. They are a poignant testimony to the devastation and heartbreak that this horrific event has caused."
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.
"The male defendant accepted his guilt on the first day of trial. The other defendant maintained her not guilty plea but, after the jury heard all the medical evidence presented, they concluded that any difficulties that she may have had did not prevent her forming an intent to kill.
"Our deepest sympathies are now with the extended family and friends of Elizabeth and Katie Edwards as they attempt to come to terms with this horrific crime."