A popular Girl Scout was killed in a "terrible and cowardly" stabbing after getting caught up in a drug turf war, court has heard.
Jodie Chesney, 17, was with friends, playing music in a park in Harold Hill, east London, when she was knifed in the back on March 1.
At about 9.20pm, her boyfriend noticed two figures coming out of the darkness noiselessly towards them.
He saw the taller of the pair swing his right arm at Jodie's back, the Old Bailey heard.
Jodie screamed and the two figures disappeared into the darkness, jurors were told.
She had suffered a deep wound to her back which bled heavily.
The court heard Jodie's boyfriend Eddie Coyle caught her as she fell and eased her to the ground.
Mr Coyle, 18, was crying and screaming at Jodie to stay awake as he held her hand.
A local resident heard her screams and came to help as Jodie's friends became "hysterical", jurors heard.
By the time an ambulance arrived, she showed no signs of life and was pronounced dead en route to hospital on the forecourt of a petrol station. Prosecutor Crispin Aylett QC told jurors that none of Jodie's friends had any idea who was responsible for the "terrible and cowardly" attack.
Following national publicity, police got a "breakthrough" when a witness reported two males getting into a stationary black Vauxhall Corsa.
Mr Aylett said but for the "chance sighting" Jodie's murder might have gone unsolved.
A couple of hours after the killing, a black Corsa registered to the defendant Manuel Petrovic was found abandoned about two miles away, he said. Following his arrest, Petrovic admitted driving to Harold Hill with a friend and two others who had gone into the park to collect money and drugs.
He denied knowing the pair were armed beforehand, the court heard. Investigators identified Petrovic's friend and the two others through CCTV footage and mobile phone data, jurors heard.
Petrovic, 20, Svenson Ong-a-kwie, 19, and two youths, aged 16 and 17, from Barking and Romford, were subsequently charged with Jodie's murder.
Mr Aylett said Jodie was a "beautiful, well liked, fun" young woman who had nothing to do with drug dealing and was unlikely to have been the intended target.
At the time of her death, Jodie was living with her father Peter, step mother Joanne and older sister Lucy in Dagenham.
The Havering Sixth Form College student had been studying three A levels and was weeks away from completing her Duke of Edinburgh gold award. Jodie's family appeared tearful in court as they listened to details of her death.
The defendants, all allegedly involved in drug dealing, deny murder.