The 20-year minimum terms handed to a teenage couple for killing a mother and daughter are being referred to the Attorney General for being too lenient.
The couple, believed to be Britain's youngest double-murderers, were 14 when they stabbed to death dinner lady Elizabeth Edwards, 49 and her 13-year-old daughter, Katie in April.
The boy, who admitted murder, stabbed both victims in the neck with a kitchen knife, attacking them as they slept at home in Spalding, Lincolnshire.
His girlfriend, who helped to plan the "cold, calculated and callous" killings, denied murder on the grounds of diminished responsibility but was found guilty after a five-day trial.
The court was told how the teenagers, now 15, had sex, shared a bath and watched four Twilight vampire films as they "revelled" in the murders.
Now the case has been referred under the "unduly lenient sentence" scheme, and law officers have 28 days to decide if any action should be taken.
A statement from the Attorney General's office offered no details of who referred the case.
"The threshold to refer cases to the Court of Appeal is very high," it noted.
"A sentence can only be regarded as unduly lenient if there has been a gross error and it is significantly below the level that any judge could have reasonably imposed after considering the facts of the case."
On sentencing earlier this month at Nottingham Crown Court, Mr Justice Haddon-Cave said the pair had a "toxic" relationship and acted in a "grotesque" way as he said the case had "few parallels in modern criminal history".
He told the teenagers: "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.
"Had you been adults you may have been facing the whole of your lives in prison for this double murder."