Police have arrested a second man over the murder of aspiring musician Umar Tufail.
Detectives investigating the murder of the 25-year-old arrested an 18-year-old on Monday and he is being held in custody at a south London police station.
Mr Tufail was shot in the head as he sat in his car metres from his home on Wharncliffe Road, South Norwood, 4.35pm July 15.
He was taken to St George Hospital but died the next day.
Police believe the suspect or suspects were in a grey car at the time of the shooting.
It is believed this vehicle pulled up alongside Umar's car and a shot was fired through the open window of the victim's car, before the suspect vehicle drove off towards Grange Road, Thornton Heath.
DCI Lee Watling, who is leading the inquiry, said: "I would reiterate my appeal for anyone who may have seen this suspect vehicle in the vicinity - or has any information on its movements before or after the shooting - to 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."
Police arrested an 18-year-old on suspicion of murder on July 23. He was bailed to return to police in August.
Anyone with information should call the incident room on 020 8247 4554; if you wish to remain anonymous call Crimestoppers on 0800 555 111.