Rhyhiem Ainsworth Barton was murdered on the evening of Saturday, 5 May 2018 in a drive by shooting.
Two people were arrested in the weeks that followed and detectives have made extensive enquiries, but three years on, his killer is still at large.
It is believed Rhyhiem was standing with a group of friends on the corner of John Ruskin Street and Camberwell New Road when he was shot.
The friends who were there will have seen what happened and will have vital information, but so far they have been reluctant to come forward.
Detectives believe that a grey BMW Series 2 Gran Tourer with the registration WT17 CFK seen on CCTV around the time of the shooting is crucial to identifying those responsible. They are confident it is this vehicle that the suspects used to make their way to and from the area.
The number plates on the vehicle at the time of the murder were not real. The true registration should have been BP17 YVV. It had been stolen during a burglary in Essex overnight on 23 December 2017 and its plates were later changed.
Officers are keen to hear from anyone who remembers seeing this vehicle in London either in its true identity or that used in connection with the murder at any time after 24 December 2017. Any information about where it was being kept, who was driving it, or who was being carried in it could prove vital.
A £20,000 reward is being offered by the police for any information – whether about the car or another aspect of the case – that leads to the successful arrest and conviction of the person or persons responsible for Rhyhiem’s murder.
Information can be given to detectives directly by calling the incident room on 0208 721 4005.
It can also be provided anonymously, to the independent charity Crimestoppers, by calling 0800 555 111 or by visiting www.crimestoppers-uk.org
Detective Inspector Jo Sidaway, from the Met’s Specialist Crime Command, said: “Rhyhiem’s murder shocked and angered people across London. We are determined to identify and bring to justice those responsible, no matter how long it takes.
“We are confident that this grey BMW Series 2 Gran Tourer was used by the gunman. We know it was stolen from Essex and that it was being used on false plates up to and beyond the date Rhyhiem was murdered. I am appealing to the public to assist us in identifying who was using this vehicle and where it was being kept.
“Did you see it parked in your street? Did you notice it left in a car park? Did you see someone putting it in a garage? Any information, no matter how small, could make the difference.
“I also want to appeal to Rhyhiem’s friends. I’m sure that some of you will know who pulled the trigger. I also know that some of you may not have the most positive view of the police and may feel that coming forward with information is a betrayal or a sign of weakness. Nothing could be further from the truth.
“Please give us the information to convict the people who killed your friend. We understand that doing so will take tremendous bravery and we are here to support you in any way we can. We are waiting for your call.”