Detectives have released a picture of a 15-year-old they want to question over the suspected murder of a teenager in a row over a mobile phone.
The CCTV image, filmed on a bus on Sunday just after 10.30pm, is believed to be the last sighting of Dawda Jallow from Peckham in southeast London, who has been missing since the stabbing.
It shows him travelling on the number 35 bus between Camberwell Green and Newington Causeway.
"If anyone knows him, if anyone knows where he has been staying, if anyone has any ideas that they should put him up for the night, I would urge them not to and call us instead," said Detective Chief Inspector Matt Bonner, who is leading the investigation.
"He must be staying somewhere and so I am urging the community for their help in letting me know where that is."
The schoolboy is described as black, clean-shaven with cropped black hair, 5ft 5in tall and stocky for his age.
He has brown eyes and speaks with a London accent, although he is a Gambian national.
Police made their fresh appeal as victim Dogan Ismail's family issued a statement about their loss.
"Our beloved son, friend, cousin, nephew and grandson has been cruelly taken away from us," they said.
"Words cannot describe how much we will miss him. We want justice for Dogan and his killer caught.
"Anyone with information, please tell the police."
The 17-year-old died from a single stab wound after a confrontation with four males on the Aylesbury estate in nearby Walworth.
He had gone there with his younger brother Orhan, 15, whose BlackBerry phone was stolen from him two days earlier.
It is believed they may have been lured there on the promise of getting it back.
A schoolfriend, who did not want to be identified, told Sky News a text message was sent inviting them to come and retrieve the phone.
DCI Bonner said: "It would appear that on the Sunday they went back onto the estate in an effort to recover that phone."
He added: "The line around him being lured there - I'm aware of that information, but it is not something that has been given to us directly, and we will pursue that with other lines of enquiry."
The incident happened just yards away from where 21-year-old Shaun Chambers, from Greenwich, was killed in a gangland attack on September 26.
Police say the two deaths are not connected.