A police officer who was run over while attempting to stop a car in Sutton, south London, on Friday has died.
PC Andrew Duncan, known to colleagues as Andy, was hit after signalling to a driver to pull over in the early hours.
The father-of-two was taken to hospital following the collision in Reigate Avenue at around 1am, but died on Sunday morning.
Tributes have been issued by the Metropolitan Police Commissioner, Sir Bernard Hogan-Howe.
He said: "I was so sad to hear that PC Andrew Duncan died this morning.
"On behalf of the Metropolitan Police family, I would like to offer my sincere condolences to his wife and children, parents, family and friends.
"Andy was a hard working and courageous policeman. He served the community as both a police officer and as a Scouting volunteer.
"The night he was injured, he was doing a job that he loved and we all had every right to expect he would return safely to his home and family - tragically that was not the case.
"We will continue to professionally and objectively investigate this incident under the oversight of Her Majesty's Coroner.
"I would urge anyone with information to contact us."
A Metropolitan Police spokesman said PC Duncan was married with a son and a daughter. He was 47 years old.
He had joined the force on March 19, 1990, and was originally posted to Battersea.
Six years later he transferred to the South-West Territorial Support Group where he served for almost seven years before moving to Hammersmith and Fulham Borough.
He subsequently joined the South-West Traffic Unit on 17 May 2004.
On Friday, the officer was working on a speed enforcement operation with a colleague, when they noticed a car driving at speed along A217 Reigate Avenue, close to its junction with Rose Hill.
A Met spokesman said PC Duncan attempted to stop the car by signalling for the driver to pull over but the driver collided with the officer and drove off towards Rosehill.
The car was found abandoned nearby, and officers are continuing to appeal to anyone who was a passenger in the car at the time to come forward.
Reigate Avenue is a residential area and officers are appealing for any witnesses who may have seen the incident to get in touch.
A 25-year-old man who was arrested on suspicion of causing serious injury whilst dangerous driving on Friday after attending a south London police station remains in custody.
He has now been arrested on suspicion of murder.