A prime suspect in the murder investigation of a teenager outside Sutton station has fled abroad, an inquest into the stabbing heard.
Student Ilyas Habibi, 17, was killed after being stabbed in the neck just after 7pm on December 5.
An inquest opened at South London Coroner's Court on Thursday, in which detectives revealed that the chief suspect had left the UK via Gatwick Airport.
A police statement said: "Police know that Ilyas arrived at Sutton High Street by train. Minutes after he came out of the station, he was involved in an altercation with a single suspect who then fled the scene.
"Following extensive enquiries, the suspect was identified. On December 11, officers found he had left the country from London Gatwick Airport on December 9. Ilya's family were informed of this. Specially trained officers continue to support them.
"Police continue to work with international partners to locate and arrest the suspect."
Police and London Ambulance Service rushed to the crime scene but the student was pronounced dead at just before 8pm.
A post-mortem examination gave the cause of death as a stab wound to the neck.
A 19-year-old man, who was arrested on suspicion of assisting an offender, was later released on bail. The inquest was adjourned to a date yet to be fixed.
In a tribute to the student his brother said: "He was caring and loving to my parents and his siblings and friends.
"He never [did] anything to anyone, was a really nice boy who was loved by everyone."
He had been doing well in his construction course at Croydon College and had a bright future ahead of him, his brother added.