A man accused of murdering Kadar Hussein in Penge did so after the victim stole a package containing drugs worth £1,500, a court has heard.
Trai Williamson - also known as Rumbles, aged 19, of no fixed address, is charged with Mr Hussein's murder.
Mr Hussein, also 19, of Upper Elmers End Road, was shot in the head in the car park on the corner of Kenilworth Road and Westbury Road at 7.57pm on May 8 last year.
He was taken to King's College Hospital but died 12 hours later.
Williamson was charged with his murder on August 8.
In late 2012 Mr Hussein took a package from Williamson and hid it in the house of his girlfriend Leah Hoyte, 20, the Old Bailey heard.
Her mother, Lisa Ward, told the court Miss Hoyte started receiving threatening phone calls.
She said: "He wanted something which Kadar had taken from him.
"Kadar wouldn't tell me what it was but apologised for bringing trouble to my house.
"I tried to find out from my daughter what it was.
"I was told by the guy calling my daughter that whatever was in the bag was worth £1,500 but I never looked inside."
After repeated phone calls to her daughter, Mrs Ward agreed to take the package to a tower block in Maple Road, Penge.
She said: "There were four black guys waiting. They were between 17 and 20 years old.
"I handed the bag to them and then I turned and went home.
"I just didn't want any trouble for my family."
When asked by defence counsel Sean Larkin why she didn't contact the police about the situation, she added: "I didn't think of it."
A friend of Mr Hussein's, who cannot be named for legal reasons, added: "He knew Rumbles was going to kill him.
"People told him he was after him.
"I think Rumbles had gone round telling people he was going to kill him.
"A couple of months ago he told me he had taken some drugs off Rumbles.
"He took them straight to Leah's house and I think he was intending to keep them there for a while.
"Leah's mum went to give the drugs back.
"When I heard what had happened I didn't question who it was.
"Everyone in Penge knew Rumbles was after Kadar."
Williamson denies murder.
The trial continues.