Police have released images of potential witnesses to the Boxing Day murder of Seydoi Diarrassouba at a Footlocker store in Oxford Street.
Diarrassouba, 18, of Mitcham, southwest London, was stabbed in the heart in broad daylight as sales crowds swarmed Britain's premier shopping street.
He was pronounced dead at the scene. Fourteen men have been arrested and bailed pending further enquiries.
Officers from the Metropolitan Police are hoping to identify witnesses in the CCTV images.
Four of the CCTV images are from the same Footlocker store and one is from the neighbouring Forever 21 store.
Det Chief Insp Kevin Concannon of the Metropolitan Police homicide and serious crime command, said: "Whilst continuing to investigate this tragic stabbing last Boxing Day, it has become apparent that there are a number of witnesses to the incident who have not yet come forward and it is vital we are able to speak to them so that we have a clear understanding of what happened that day
"I would encourage anyone who was there and who has not yet spoken to police to contact us."
Police are urging anyone who may have witnessed the attack or has any information surrounding it to contact the incident room on 020 8358 0100 or if you wish to remain anonymous phone Crimestoppers on 0800 555 111.