Police investigating the murder of an aspiring musician gunned down outside his home believe the suspects were driving a grey car.
The 25-year-old was taken by ambulance to hospital, where he died on the following day from a single gunshot wound to the head.
Trident detectives who are investigating his death believe the suspect or suspects were in a grey car at the time of the shooting.
Officers believe the vehicle pulled up alongside Umar's car and a shot was fired, before driving off towards Grange Road, Thornton Heath.
No arrests have been made and officers say they have an open mind as to any motive.
DCI Lee Watling said: "It is essential anyone who may have seen this suspect vehicle in the vicinity, or has any information on its movements before or after the shooting, does come forward.
"It is suggested that the vehicle may have been a Vauxhall Corsa - coincidently the same make as Umar's car, though his was red.
"However we must retain an open mind at present on the actual make and model of the car we are seeking, that is why we need the public's help."
Anyone with information should call the incident room on 0208 247 4554, or Crimestoppers anonymously on 0800 555 111.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article