Half a kilogram of cocaine concealed within a DHL consignment, sent from Hollywood Boulevard in California and destined for Sydney's western suburbs.

Under surveillance by police investigating a transnational cocaine syndicate, Youssef Ahmad and Mohommed El-Khair are spotted in 2015 picking up the parcel in Bankstown.

But when the pair opened the consignment, they found blocks of wood, placed their by the FBI days earlier, in replacement of the cocaine.

The heated exchange and disbelief that ensued between Ahmad and El-Khair formed part of the police allegation that the pair had knowledge of the cocaine shipment and were willing players in the international importation.

Police started investigating money laundering and drug supply after authorities suspected cocaine was making its way into Australia from Southern California via air freight and mail.

This week the strike force, including the NSW Organised Crime Squad and Australia Federal Police, arrested its 30th person, after seizing more than $47 million worth of drugs and $1.2 million in cash.

One of the networks at the centre of the sweeping investigation involved El-Khair, Alfred Manukyan and Ahmad, the younger brother of slain underworld figure Wally Ahmad.

The details of how the syndicate allegedly operated have been laid bare in a statement of police facts tendered in court after Manukyan's arrest in Sydney on February 3.

More than 500 phone calls were intercepted and many hours of surveillance carried out for over a year as police pieced together how the cocaine network operated.

Machinery parts and sporting equipment were allegedly filled with cocaine before being packed in boxes and dropped at unassuming postage centres in America.

Manukyan is accused of fulfilling this role, allegedly sourcing cocaine for Ahmad and sending it to Australia from Southern California on three occasions.

According to the facts, in September 2015, Manukyan was seen sending a box marked "used motor parts" from a shopping centre in North Hollywood to an ink business in Silverwater.

When the parcel reached customs in Australia, authorities allegedly found about 970 grams of cocaine inside.

El-Khair was seen loitering around the Silverwater business where the box was meant to arrive, making call after call to DHL trying to hunt down the parcel's whereabouts.

On another occasion, the FBI intercepted a parcel Manukyan had allegedly sent and found 190 grams of cocaine concealed in baseball equipment.

Police allege Ahmad travelled to Los Angeles in 2015 to meet Manukyan and was taken to various distribution points in the city.

In a bid to allegedly throw off authorities, the syndicate also allegedly sent a number of "dry runs" - packages without drugs in them - on their usual route.

Last June, in simultaneous raids, Ahmad and El-Khair were arrested at their Punchbowl homes and charged with drug importation.

Police allege Ahmed was "the ringleader of the Australian drug network" and had a number of people, including El-Khair, carrying out activities at his behest, the facts state.

Several months later in February, Manukyan arrived in Sydney, where detectives were waiting.

The 47-year-old, who is now facing three drug importation charges, was arrested on route to Sydney International Airport on February 3.

Police say they expect further charges to be laid with investigations still going in NSW and America.

"We are proud of the significant drug and cash seizures, but the real focus is disrupting and dismantling criminal networks," Organised Crime Squad Detective Superintendent Scott Cook said.

"The members of this criminal network have been charged with more than 100 offences relating to the importation of drugs, money laundering, fraud, and a range of other matters."