A teenager convicted of murdering a schoolgirl at a 16th birthday party has been detained for at least 14 years.
Beatriz Martins-Paes kept a hit list of people she hated
Beatriz Martins-Paes killed Charlotte Polius, 15, when she plunged a knife into her on the dance floor at a party in Ilford, east London, last April.
The Old Bailey heard Martins-Paes, 18, of Brentwood, Essex, regularly carried knives in a bag and had a hit list of people she hated, including a teacher.
She threatened Charlotte before stabbing her through the heart.
Afterwards, she removed the knife, put it back in her bag and tried to escape from the party, leaving her victim to die, the court heard.
Other young girls at the party were left to watch the "horrific scene", judge Giles Forrester said.
"You robbed Charlotte of her young life and caused deep distress and deprivation to her young friends," he said.
The murder had followed a feud between Martin-Paes and another teenage girl a month earlier, said Aftab Jafferjee, prosecuting.
Although Charlotte, of Stratford, east London, had been present but not involved, she became the unwitting victim as Martins-Paes was determined to continue the feud at any cost.
Martins-Paes had admitted manslaughter, but denied murder saying she had not intended to seriously harm Charlotte.
She had earlier told the court: "I didn't mean to stab her at all. None of that was supposed to happen. I didn't think of the consequences."
The judge however said he was in no doubt that she had been looking for a fight.
Charlotte, 15, was stabbed through the heart
"You mixed with other girls in whose eyes you wanted to look tough.
"This case illustrates once again the utter folly of persons - even female teenagers such as you - who nowadays arm themselves with knives and carry them in public," he said.
Charlotte's mother Mary Foley said her faith had helped her to forgive her daughter's killer and she intended to visit her in prison.
"She is a young lady who has had a tough life. She has killed Charlotte, but she needs help. I just hope in 14 years she will change," she added.
The sentencing comes as Martins-Paes father, Julio, is being sought by police in connection with the attempted murder of his 40-year-old partner last month.
The unnamed woman is recovering in hospital after she was stabbed in the chest and thigh in a car in Dagenham, east London.