Following the collision, Al-Karim Visram ran over the 78-year-old's legs after his windscreen was damaged making it '"virtually impossible" to see through it safety, the Metropolitan Police said.
On March 15 last year, Visram, was driving a black Hyundai i20 in Alexandra Avenue at 6.10pm when he struck 78-year-old Hansraj Damji, the Met said.
Mr Damji was crossing the road on a zebra crossing at the time of the collision.
The impact of the collision caused "significant damage" to Visram's windscreen.
Instead of stopping, the 38-year-old drove his vehicle to a side road but ran over Mr Damji's legs in the process and caused him further injuries.
Mr Damji was taken to hospital where he was treated for his injuries including a broken neck, back and leg.
On April 19, Mr Damji died after contracting pneumonia.
A post-mortem examination was carried out on April 23 and established a casual link between the collision and Mr Damji's death, the Met Police said.
Formal cause of death was given as pneumonia and injuries to the left leg and spine.
Visram was charged with causing death by dangerous driving.
Al-Karim Visram, on Pine Gardens, was sentenced to three years in prison on Wednesday (November 30) at Harrow Crown Court after he was found guilty of causing death by dangerous driving.
He was disqualified from driving for three years and has been ordered to take an extended re-test.
Visram had been found guilty of causing death by dangerous driving following a trial at Harrow Crown Court on 9 November.
Detective sergeant Jane Mallett, of the serious collision investigation unit, said: "Not only did Visram's initial act of dangerous driving cause significant injuries to Mr Damji, he compounded this by running over him a second time when it was impossible to see clearly through his damaged windscreen.
"I hope now that the culprit has been sentenced, Mr Damji's family can have some form of closure".
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