Two people including a 16-year-old boy, who are accused of murdering teenager Jodie Chesney in an east London park, have appeared in court.
Manuel Petrovic, 20, of Romford, was remanded in custody after appearing at the Old Bailey via videolink.
The teenage boy, who cannot be named, then appeared later at Barkingside Magistrates' Court.
Jodie, 17, was knifed in the back near a playground in Harold Hill, Romford, on 1 March.
A further four arrests have been made in connection with the investigation, the Metropolitan Police said.
An 18-year-old man, from Romford, was arrested on suspicion of murder and is being held in custody.
A man, 50, and woman, 38, both from Dagenham, and a 17-year-old boy have all been arrested on suspicion of assisting an offender.
All four remain in custody while inquiries continue, detectives added.
Jodie was the fifth teenager to be stabbed to death in the capital so far this year.
Her father Peter led tributes, describing his daughter, who was a keen Scout, as a "great girl" and a "proud geek".
Tributes have been left outside the park where Jodie died, and purple ribbons - her favourite colour - have been hung across Harold Hill and Romford.
Jodie was pronounced dead after police were called to the park near St Neot's Road at 21:25 GMT on 1 March.
She was with friends at the time of the attack.
A post-mortem examination gave the cause of her death as trauma and haemorrhage.