CCTV released of mystery cars at scene of Sydney teenager's shooting death

New security vision showing two suspicious cars has been released by police as they investigate the shooting death of a Sydney teenager in February.

Omar Elomar, 18, was found on the road with a gunshot wound to his chest on Cabramatta Avenue at Miller, near Liverpool, just after 11pm on Saturday February 15.

Mr Elomar, a relative of notorious Islamic State fighter Mohamed Elomar, was shot once in the chest at close range as he sat in the driver's seat of a car.

He died at the scene.

The CCTV vision released by NSW Police today shows two cars seen on the street that night.

A silver sedan was seen driving along Cabramatta Avenue around the time of the shooting, while a red hatchback drove away from the scene shortly after.

Police are due to give an update on the two cars later this morning along with Mr Elomar's mother.

On February 26, an 18-year-old man appeared in Central Local Court on charged with murder.

Homicide Squad Commander Detective Superintendent Danny Doherty earlier said the shooting was linked to an alleged altercation between two teenagers the day before Mr Elomar was gunned down.

"This other group have approached the vehicle that Omar was in and they've shot him down in cold blood," Mr Doherty said.

Detectives say Mr Elomar was not known to police and his death was unrelated to his terrorist relative, who was killed in Syria.