Pictures of shoppers who may have vital information about the murder of a Mitcham teenager have been released by the police.

Seydou Diarrassouba was killed among crowds of shoppers on Oxford Street during the Boxing Day sales last year. Now CCTV pictures taken near the scene of the crime have been published, as police try and trace witnesses who have not yet come forward.

Mr Diarrassouba, an 18-year-old from the Phipps Bridge estate, was fatally stabbed in the Foot Locker store at about 1.45pm on December 26. The five images released on Monday are from inside the trainer shop and nearby clothes outlet Forever 21.

Detective Chief Inspector Kevin Concannon, of the Met Police's 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."

Last month Thulani Khumalo, a 20-year-old from Hackney, was charged with Mr Diarrassouba's murder. Five other men have been arrested and bailed to return to the police this month in connection with the crime.

Police asked witnesses to call the incident room on 020 8358 0100 or Crimestoppers on 0800 555 111.