Police were called at 7.48am on Thursday, 21 October to Sandy Hill Road, SE18 to a man collapsed in the street.
London Ambulance Service attended and Emmanuel was pronounced dead at the scene.
A post mortem found the cause of death to be a single stab wound.
The murder investigation is being led by Detective Chief Inspector Richard Leonard, from the Met’s Specialist Crime Command.
Emmanuel is believed to have been attacked by a group of men a few hours before he was found
DCI Leonard said: “We are specifically appealing for anyone who was in Burridge Place or Sandy Hill Road from 11.40pm to 11.45pm on Wednesday, 20 October.
“Analysis of CCTV footage shows Emmanuel was surrounded by a group of males and we would like to identify who they are.
“Similarly, please check any doorbell or dashcam footage in case you have captured something that could prove useful for our investigation. No piece of information is too small.”
There have been no arrests at this stage. To provide information, call the incident room on 0208 721 4622.
To remain completely anonymous phone Crimestoppers on 0800 555 111.