Two people who fled the scene of a fatal car crash on Adelaide Avenue are being asked to come forward to police.
Police now believe two other people were in the car when it crashed into a concrete barrier on the State Circle in April.
The other people in the car are believed to have climbed out of the car and collected by a second vehicle that then fled the scene, police said.
The collision led to the death of a 15-year-old Indigenous teenager, who was taken to hospital with injuries but later passed away.
Detective Sergeant Jonathon Turkich from ACT Policing's Major Collision Team said police are urging these two people to come forward.
"To a certain extent, it is understandable that people panic in traumatic situations like this, however I cannot understand how you leave any human being, let alone someone you likely know, on the side of the road critically injured," he said.
"This must be weighing very heavily on the conscience of these two people."
Detective Sergeant Turkich said he would implore the people to consider the family of the boy who died.
"Be brave now and approach police so we can bring some answers to the family and friends of the young man who lost his life," he said.
"It may provide you with the opportunity for some relief and support yourself rather than feeling like you're looking over your shoulder for the rest of your life."
Investigators are also asking anyone who has information about the two other occupants or the second vehicle that arrived at the collision scene to come forward.
Anyone who can assist police is urged to contact Crime Stoppers on 1800 333 000, or via the Crime Stoppers ACT website. Please quote 7726381. Information can be provided anonymously.
