Julie remained in a coma for 19 weeks following the attack but never regained consciousness and died in hospital on September 21 last year.
Jonathan Turner, QC, prosecuting, said the two girls ‘actively disliked’ one another by the time of the attack on May 7. ‘What lay behind this antagonism, the crown cannot say with any certainty,’ he said.
‘But there seems to have been a row brewing between them over certain allegations that Julie had been making about the defendant, and some boyfriend or boyfriends of hers.’
He said the gossip had been spread via the mobile phone network using ‘telephonic sites’.
The defendant, now 16, spotted Julie close to a William Hill betting shop in Falcon Road, Clapham, and angrily snapped: ‘What do you think you are doing in Clapham? Why are you here?’
Mr Turner said: ‘There seems to have been some territorial issue between them.’
Just moments after the chance meeting, the defendant was allegedly seen to thrust an overarm blow at Julie’s head.
‘He described the 16 year-old as reaching into her bag and pulling out a pin-tail comb and stabbing Julie with it not once but twice,’ Mr Turner said. 'The first one was to Julie’s collarbone, but it barely penetrated, and it was the second blow that went into her making a noise, he said, like a noise it makes when we kill a goat back home.’
Police arrested the alleged killer as she walked to her home in Pimlico in the early hours the next day.
She is said to have initially given officers a false name, before asking: ‘Is it about the fight yesterday? I don’t think I did anything wrong.’
Upon searching her, police found a metal comb in her handbag which was later found to have only her own DNA on it.