Two further arrests have been made in connection with the murder of a 17-year-old in Islington.
Nedim Bilgin, 17, was knifed to death in Caledonian Road, Islington, north London, shortly before 7pm on Tuesday night.
An 18-year-old male was arrested on suspicion of murder on Thursday and is currently being held in custody, while a 22-year-old man was arrested on suspicion of assisting an offender.
The second man has been released on bail, police said.
Officers previously arrested two boys, aged 16 and 17, on suspicion of murder close to the scene of the crime within minutes of the killing.
Both have since been bailed pending enquiries.
An 18-year-old man who was arrested at a residential address on suspicion of murder a short time after the killing has also been released on bail.
Nedim became the eighth person to die as a result of violence in the capital so far this year.
A post-mortem examination found the cause of death to be a knife wound.
Police are appealing for witnesses to come forward.
Investigating officer DCI Mark Wrigley said: “This fatal knife attack took place just before 7pm in an area that lots of people would have been walking or driving through.
“We have had reports of people seen running around and on pedal bikes near Caledonian Road junction with Tilloch Street at around this time.
“Were you there? Did you see anything suspicious? Did you record footage before or after the attack or did have you vehicle’s dashcam on? We need to hear from you to help build a clearer picture of what happened.”
Temporary Chief Superintendent Nick Davies said: “Five arrests have been made so far. The investigation continues apace. My officers and those from the Homicide and Major Crime Command are carrying out a number of detailed forensic and CCTV footage related enquiries.
“I completely understand the alarm and concern it has raised from those who live and work in the area. Officers are continuing their painstaking work to piece together the details of the attack.”