The search comes as two men were arrested in simultaneous raids in greater Sydney this morning.

Mejid, 44, was gunned down outside his Simmat Avenue, Condell Park home on October 19 last year, sparking an escalation in an ongoing gangland war.

On Wednesday morning investigations led Criminal Groups Squad detectives to execute a Firearms Prohibition Order search and six search warrants at Liverpool, Peakhurst, Bringelly and at an address on Walker St, Helensburgh.

A 38-year-old man was arrested at a home at Liverpool and taken to Liverpool Police Station, where he is expected to be charged over the alleged murder.

A 44-year-old man was arrested at Croydon and taken to Burwood Police Station, where he is expected to be charged in relation to the concealment of a white BMW allegedly used in the incident.

Detectives from the State Crime Command's Criminal Groups Squad established Strike Force Courier to investigate, twice appealing to the public for information and releasing CCTV footage of three cars of interest.

The cars - a grey Toyota Rav 4, a matte black Mercedes Benz and a white BMW 328i were allegedly seen travelling in convoy in the area in the lead-up to the execution.

About midday on Wednesday, police removed three high-end performance vehicles from an outbuilding at the Helensburgh acreage and loaded them onto a car carrier.

Bassam Hamzy was initially jailed for 21 years for shooting a teenager dead on a Sydney nightclub strip in 1999, when he was 19.

He started the Brothers 4 Life gang while in jail, after converting to radical Islam. The gang was borne out of internal disputes between a Lebanese Australian Bankstown chapter and an Afghan Australian Blacktown chapter, and has built a history steeped in violence and death.

On June 17 Bassam's cousin, Sydney crime boss Bilal Hamze, 34, shot dead as he departed a Bridge Street Sydney restaurant. Hamze had spent the last months of his life with a bounty on his head and had been warned by detectives they were concerned about an ongoing feud with a rival family, the Alameddines.

In April police charged Bassam Hamzy with falsifying documents relating to an investigation into the murder of 15-year-old Brayden Dillon. The teen was shot dead in his sleep at his Glenfield home in Sydney's south-west on Good Friday in 2017.

Strike Force Courier detectives were assisted throughout the operation by Raptor Squad and officers from South West Metropolitan Region Enforcement Squad.

Investigations under Strike Force Courier are continuing.

Update, 2.30pm:

Police have charged a 38-year-old man with the murder of Mejid Hamzy. He was refused bail to appear in Liverpool Local Court today, also charged with 11 proceeds of crime offences, driving while disqualified, police pursuit, drive manner dangerous, possess prohibited drug and facilitate organised car rebirthing activity.

Police will allege in court that the man was involved in the planning of the murder.

A 44-year-old man arrested at Croydon has been charged with six offences including; deal with property proceeds of crime and five drug crimes including manufacture indictable quantity prohibited drug.

Police will allege in court that the man was involved in concealing the BMW used in the incident.

The man was refused bail to appear at Burwood Local Court today

State Crime Commander, Acting Assistant Commissioner Darren Bennett, said today's arrests were the result of nearly 10 months of investigations by Strike Force Courier detectives.

"Since October last year, investigators have reviewed hours of CCTV vision and spoken to numerous witnesses to ensure those responsible are charged and put before the courts," Acting Assistant Commissioner Bennett said.

"These investigations remain ongoing and the NSW Police Force will not rest until all the perpetrators of these crimes are behind bars.

"I want to reassure the community that these public acts of violence will not be tolerated by police and that detectives across the State Crime Command are working closely to investigate a number of shooting incidents in the past year," Acting Assistant Commissioner Bennett said.

EARLIER: A police operation is unfolding in Helensburgh on Wednesday morning with a number of police vehicles lined up on Walker Street.

A local resident (who wished not to be named) was feeding chickens on his property when he heard shouting before noticing a contingent of about 10 "marked and unmarked police vehicles" arrive at a nearby property around 7:30am.

"I hear commotion and I look up and there's SWAT officers in what I would call balaclavas and fully suited, walking in formation towards the house, then there's other officers walking in formation to a rear shed," the witness told the Mercury.

"Two cars drove back to the rear shed and opened that up. They then searched the rear stables."

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The resident said he watched two different people be interviewed by police at the property, and noted the balaclava-clad officers inside the main home.

MORE TO COME ...