Detectives are revisiting the spot where a schoolboy was killed "protecting" his younger brother.
A week after aspiring rapper Negus McClean, 15, was stabbed in the heart, officers will return to Edmonton, north London, where he was fatally injured.
They hope to speak to people near Westminster Road as part of a fresh appeal for information.
Detective Chief Inspector Stephen Clayman of the Met's homicide and serious crime command said: "I would urge anyone with information about the murder of Negus McClean to come forward and speak to my team.
"People may think that incidents such as Negus's murder are not their problem but they have a devastating effect on family, friends and the community as a whole.
"If you know something, no matter how insignificant it may seem, please don't hold this back - contact the incident room on 020 8345 3775, and your information will be treated in the strictest of confidence."
Negus was found with stab wounds to his chest and thigh at around 7.30pm last Sunday.
It is believed that around 13 young black men, thought to have been on bicycles, chased him prior to the attack. He was taken to the Royal London Hospital but died later that night.
His cousin Noel, 25, later said the teenager was killed defending his brother in a "selfless act".
A total of seven people have been questioned over his murder.