A millionaire's daughter has been found guilty of killing an elderly woman after writing an 18-page murder manual.
DNA from Adeyoola was found on Mrs Mendel
Kemi Adeyoola was 17 when she stabbed 84-year-old Anne Mendel 14 times during a burglary in March 2005 at her home in Golders Green, north-west London.
The Old Bailey heard Adeyoola had written a manual on how she would kill an elderly victim after robbing them.
The teenager's father, Bola Adeyoola, who runs a property management company, said: "What she did was evil."
Adeyoola, who was found guilty of murder on a 10-2 majority, is expected to be sentenced on Wednesday.
Mrs Mendel, who was a former neighbour of Adeyoola, was found by her husband covered in coats in the hallway of their home.
Leonard Mendel, 81, told the court he tried to give his wife of 50 years the kiss of life when he returned from an errand to find the hall phone wires cut and blood on the walls.
The prosecution said Adeyoola had chosen Mrs Mendel as a "soft target" on which to practise before finding a "rich, elderly and defenceless" woman to kill for her money.
Adeyoola, now 18, had written plans for the killing while serving a sentence for shoplifting. Her aim was to make £3m.
But she claimed that the 18-page neatly-written murder manual found in a cell search at Bullwood Hall, Essex, was the draft of a crime thriller.
Anne Mendel's body was found by her husband
Adeyoola, who disposed of her bloody clothing, might have got away with murder but for a tiny speck of DNA found on Mrs Mendel's hand.
Sir Allan Green QC, prosecuting, said there were several similarities between what was written in the manual and the actual murder of Mrs Mendel, including killing her in the hall.
He added: "This was, it is very unpleasant to contemplate, a dry run, an experiment to kill a woman she knew, an easy target - let's see how it is done."
After the verdict, it emerged that Adeyoola's murder manual was passed to Barnet Youth Offending Team, which includes local police, after her three months in Bullwood Hall expired.
The team supervised her for a three-month licence period. A month after it expired, she killed Mrs Mendel.
A statement released by the family after the verdict read: "Mrs Mendel was a person whose whole life was taken up with kindness and giving up of herself for others.
"The unjust end she met having so much taken away in such an undeserving manner left us in total shock."