Salim Coulter was shot in the head as he sat in the passenger seat of a parked car in Walham Grove, near the junction with North End Road.
There have been no arrests one week on from the murder and detectives are returning to the scene on Monday (December 12) to investigate further.
A statement from Salim's family said: “We are shocked by what's happened and still trying to understand and make sense as to why he was taken from us.
“Salim was a good boy, aspiring to be an engineer which was something he was passionate about so he could take care of his beloved mother who he lived with.
“He touched so many people's lives and was loved by everyone because he had a pure heart, he was kind and gentle to everyone he met.
“He was devout to his faith and a good example to his peers.”
The Metropolitan Police were called at around 9.30pm on Monday December 5 by a member of the public after reports of a gun shot in Walham Grove.
Officers and the London Ambulance Service found a man – later identified as Salim – suffering from a gun shot wound to the head, sat in the front passenger seat of the car.
He was pronounced dead at the scene.
Salim had been out that evening with a friend and had stopped for something to eat at Jerky Chicken in Walham Grove.
After the pair left the restaurant they returned to the silver and black Renault Captur, and as Salim got into the front passenger seat he was shot once in the head.
The suspect then fled on foot away from North End Road towards the Harwood Arms pub near the junction with Walham Grove and Farm Lane.
Detective Inspector Noel McHugh, from the Homicide and Major Crime Command of the Met Police, said: “The person responsible had most likely been lying in wait for him to leave the restaurant.
“At this stage in our investigation we are keeping an open mind regarding motive and will be trying to establish the victim's precise movements in the day running up to his murder.
“This is a low crime area. Salim's murder has shocked the local community.
“There is a strong neighbourly spirit in the area and I would encourage the very vigilant local community to contact police with anything that they saw during and after the attack.”
DI McHugh said police are appealing for anyone who might have seen someone loitering in the area from 8.30pm or running away at 9.30pm.
Police are hoping to speak to any cyclists or drivers who were in Walham Grove or North End Road from 8.30pm who may have captured images on their own cameras.
The Met said Salim's family are being supported by specially trained family liaison officers.
Salim, who lived with family in White City , was training to be an engineer.
A post-mortem examination held at Uxbridge Mortuary on Thursday (December 8) found Salim died from a gun shot wound to the head.
Anyone with information is asked to call the police Incident Room on 02087858099 or Crimestoppers anonymously on 0800 555 111.
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