Jodie Chesney was stabbed in the back by mistake after her killer “rid out on the wrong people”, according to the alleged getaway driver.
Manuel Petrovic, 20, is one of four youths jointly accused over the death of the popular 17-year-old in Amy's Park in Harold Hill on March 1.
While on remand over the killing, Mr Petrovic protested his innocence, saying he was only asked to drive to Harold Hill, and not why.
During a covertly recorded prison visit by two female friends on May 24, he said: "I'm going to say I'm a drug dealer, I broke the law with my driving. I'm not into murder. I ain't going to go guilty for something I have not done. I'm no murderer."
During a second visit on August 3, Mr Petrovic allegedly said to a friend that Jodie was stabbed after his co-defendant Svenson Ong-a-Kwie was "cheffed" [stabbed].
According to a transcript of the conversation read out in court, Mr Petrovic said: "They went to bang out on their ops and banged out the wrong people."
Asked how he knew that, Mr Petrovic replied: "Uh? Because I know that ... It was to do with Svenson's op - they cheffed him up a couple of month or something, a couple of months before.
"Someone give him the drop, he went to ride out and rid out on the wrong people in the park and they thought it was them because they chill in that area.
"That's why she got it from behind."
Asked where the tip-off came from, Mr Petrovic replied: "They got their drop their self bruv. Because they were in a cab in Harold Hill when they text me saying 'ring me, ring me asap, need to come and see you asap'."
During the conversations in prison, Mr Petrovic also talked of his hope to "bust the case".
His friend told him he should "take this opportunity" if he got off the charge and take a "nine to five job".
Mr Petrovic, 20, from Collier Row, Svenson Ong-a-kwie, 19, from Collier Row, and two youths, aged 16 and 17, from Barking and Romford, all deny murder.
Jurors were told of an incident before Jodie's death in which Mr Ong-a-Kwie was found with a makeshift bandage around his left thigh.
The defendant was said to have been vague about it, saying: "Basically, this is what happened. They pulled up here in a car, jumped out and stabbed me in the leg."
The court heard Mr Petrovic had convictions dating back to 2013 including for possession of cannabis and handling stolen goods.
Mr Ong-a-Kwie had pleaded guilty to possession of class A and B drugs when he was 16.
He also had a conviction for the supply of cocaine and having stolen goods, jurors were told.
According to agreed facts read to court, the 17-year-old defendant, then aged 14, had been involved in an incident in a shop in which a member of staff was attacked with a screwdriver.
The youth went on to plead guilty to assault occasioning actual bodily harm and possessing a pointed article.
The trial was adjourned until Friday when the defence is due to start.
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