A jury has retired to consider its verdict in the murder trial of a 15-year-old girl accused of stabbing and smothering a Scots dinner lady and her daughter.

The defendant, who cannot be identified because of her age, has admitted the manslaughter of Elizabeth Edwards, 49, and her 13-year-old daughter Katie, originally from Edinburgh.

The 15-year-old, who is said by a defence psychiatrist to have been suffering from a mental disorder, denies murdering the victims on the grounds of diminished responsibility.

The Crown submits the youngster was not mentally ill at the time of the killings and is guilty of the "cold, calculated and callous" murders at the victims' home in Spalding, Lincolnshire.

A five-day trial at Nottingham Crown Court has heard Ms Edwards and her daughter were found dead by police on Friday, April 15, after being stabbed by the female defendant's 14-year-old boyfriend, who has admitted murder.

The girl, who was also 14 at the time, is alleged by the prosecution to have shown "sheer brutality and utter contempt" for the victims, helping the boy to carry out the killings "to the letter" after days of planning.

Summing up the evidence in the case to the jury panel, trial judge Mr Justice Haddon-Cave said the sole issue for the jury was whether or not the girl was suffering from an abnormality of mental functioning at the time of the killings.