Five men are still wanted over the deadly shooting of a teenager related to a slain Islamic State terrorist near a park in Western Sydney two weeks ago, a court has heard.

Key points: The accused man has been refused bail and will face court today

The accused man has been refused bail and will face court today Police have described Mr Elomar's shooting as an "unprovoked" attack

Police have described Mr Elomar's shooting as an "unprovoked" attack The 18-year-old man was last week charged with concealing a serious crime

An 18-year-old man, who cannot be named for legal reasons, was dressed in a hooded jumper when he faced Central Local Court from his police cell at Surry Hills this afternoon

The Campbelltown man was first arrested a week ago when heavily-armed officers stormed a home at Cartwright, seizing a car, clothes and a mobile phone, before he was charged with concealing information about the crime.

Last night, detectives formally charged him with the murder of Omar Elomar, who was gunned down on Cabramatta Avenue and left to die in a car parked outside a home at Miller.

Detective Superintendent Danny Doherty, who has only recently been appointed the new homicide boss for NSW Police, previously described the shooting as "cold-blooded murder".

Omar Elomar is related to Mohamed Elomar, who infamously posed in photos holding severed human heads while fighting for Islamic State in Syria.

Mohamed Elomar was killed during a coalition airstrike in 2015, but police say Omar Elomar had a clean criminal history and was "an innocent man".

Omar Elomar was killed at Cabramatta Avenue at Miller earlier this month. ( ABC News )

The 18-year-old was trying to resolve a fight between a younger relative and another man when he took a bullet to the chest from a shotgun before shocked neighbours heard a car speed off.

The police prosecutor sought a three-month adjournment to the case this afternoon because "the investigation is still taking place".

"Your honour, there are still five persons outstanding at this time that police are aware of," he said.

Omar Juweinat, a lawyer representing the alleged killer, didn't oppose the request given "this is one of a number of offenders".

When Detective Superintendent Doherty fronted the cameras at NSW Police headquarters last week, he asked the public for help in tracking down a "group of young men of Pacific Islander appearance".

No description of their getaway car was given, but the ABC understands detectives are close to tracking them down over the brazen shooting.

The alleged killer will remain behind bars, but is expected to apply for release when the case returns to Liverpool Court in May.