Police seized a taxi at Glenwood in their investigation into the hit-run death of Andrew Heffernan.
Mr Heffernan, 23, from Glenhaven, was fatally injured after being struck by a vehicle on Old Castle Hill Road about 1am Saturday, May 26.
Following investigations by The Hills police and metropolitan crash investigators, a taxi was seized from an address in Glenwood on Sunday morning.
View raw footage of the taxi supplied by Police Media below:
Inspector Lagats denied media reports police suspect Mr Heffernan may have been hit by a vehicle after a disagreement over a taxi fare.
"That's not our line at the moment. We still haven't worked out how the accident happened at the moment ... so if it's in the media, it has to come from a source that is outside the police," he said this morning.
"If someone has that information, we would love them to come forward and contact people with that if they are a witness."
The ABC said it understood "witnesses have told police Mr Heffernan had been talking to the driver and was hanging on to the taxi as it suddenly accelerated".
Police said the car has been taken for forensic examination.
Investigators said they believe there are strong links between the incident and the vehicle seized.
The 39-year-old male owner of the cab has been spoken to by police but is yet to provide a formal statement.
Mr Heffernan's devastated father, Kym, yesterday made an impassioned plea for help in finding out who killed his son.
"We just want to know what happened, we just want closure," Mr Heffernan said, on channel 10.
"It's like a parent's worst nightmare."
Mr Heffernan said his son's career was on the rise and "he was in the prime of his life" at the time of his death, having been drinking with old friends at the nearby Hillside Tavern.
"His career was on the rise, he was in the prime of his life," Mr Heffernan said.
"He'd just got the new job and he was excited about that.
"He's got three younger brothers who idolise him.
"They thought he was the best thing ever."
He was struck by a car sometime between 12.30am and 1am yesterday morning, outside Castle Towers.
Police continue to urge anyone who witnessed the incident or who has information about the vehicle involved to contact Crime Stoppers, 1800 333 000.