Crime Desk Detectives will be appealing for information in Harrow Town Centre on Thursday 4 November, two weeks on from the murder of Lee John Hook.
They will be handing out leaflets and speaking to people to trace any witnesses they have not previously spoken to.
Police were called at approximately 01:40hrs on Friday 22 October to Kymberley Road to reports of a man shot.
Officers and the London Ambulance Service attended and found a man inside a blue VW Golf suffering a gunshot wound.
He was taken to a north London hospital where he died on Wednesday 27 October.
A post-mortem gave cause of death as a gunshot wound to the head.
Detective Inspector Andy Partridge of the Homicide and Serious Crime Command at Hendon, said: "Events leading up to the shooting are still unclear. We are appealing to anyone who may have been in the nearby Royal Oak pub and may have seen or heard anything which may have led up to the shooting.
"We understand that a number of witnesses had rushed to the assistance of the victim offering first aid - these people have yet to come forward and we urge them to speak to us as they may have vital information."
Anyone with information is asked to call the Incident Room at Hendon on 020 8358 0400; if you wish to remain anonymous please call Crimestoppers on 0800 555 111.
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