A "cold-blooded killer" who murdered a Jewish pensioner in her home has failed in a bid to have her sentence cut.
Kemi Adeyoola was 17 when she stabbed former neighbour Anne Mendel 14 times in March 2005.
She was jailed for life at the Old Bailey in June 2006, with her minimum term set at 20 years.
Adeyoola, now 28, tried to have her tariff reduced by arguing she had made "exceptional and unforeseen progress" during her time behind bars.
But refusing to alter her minimum jail term, High Court judge Mr Justice Singh said: "There is clearly a lot of work still to be done."
Adeyoola and her family used to live next to 84-year-old Mrs Mendel and her husband, who discovered her body covered in coats in the hallway of their home.
Mr Justice Singh said: "It is clear that not only was the victim targeted, both for financial gain and in order to experience an act of killing, but the victim had previously been kind to this applicant."
Mrs Mendel's murder was intended to be a "practice run" for a plot to find and kill an elderly, rich woman for her money. Adeyoola hoped to make £3 million and wrote an 18-page murder manual.
When she was jailed, Adeyoola was described as "intelligent, manipulative and skilled in deceit" and a "remorseless and cold-blooded killer".
Lawyers for Adeyoola said she had achieved a number of "treatment goals", held a position of trust within the prison and had started an Open University course.
However, Mr Justice Singh said a prison report pointed to poor behaviour including "deliberately stealing items from her peers" and a "long history of pushing boundaries".
There was also evidence of prisoners being intimidated by her obsessive behaviour towards them and she has a history of abusing substances while in custody.
Refusing to reduce her tariff in a written decision published last Friday, Mr Justice Singh said that, although she had made "some progress", it could not be said to be "exceptional".
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