Ferenc 'David' Stemler was found dead, shot several times, on Broughton Street at Canterbury after Police were called to the southwest neighbourhood in the small hours of Thursday, July 27.

Burwood Police and the state's homicide squad opened investigations into Stemler's death, but the matter was quickly handed to Task Force Magnus, which NSW Police set up to investigate links between organised criminal activity in Sydney last year.

After months of inquiries, officers arrested 23-year-old expectant mother Rhylee Peta Stig in Wetherill Park on Wednesday morning around 7am.

Stig and a 27-year-old man, Sione Langi, who was transferred from Parklea Correctional Centre, have both been charged with murder.

Both remain in custody after Stig was refused bail in Fairfield Local Court on Wednesday and Langi, who was arrested in November over another July shooting in Sydney, was similarly refused bail in Blacktown Local Court on Thursday.

Langi was allegedly involved with two other men in a daylight shooting at an inner-west hair salon at Marrickville on July 7 that wounded two men aged 20 and 33.

Police allege that Stig, who was unknown to Police until this week's arrest, was a "lackey" who helped orchestrate the bloody hit on Stemler, who Police say had associations with organised crime in Sydney's underworld but was not a "major player".

"We are not making any suggestion about Stemler's involvement in organised crime," Detective Inspector Virginia Gorman of the state's Homicide Squad said earlier this week. "He was known to Police. He was a local man and grew up with a number of people in the area who have also been victims of these crimes, so there are associations, but that doesn't make him a major player in organised crime.

"My understanding is that Mr Stemler and the victims of the Marrickville shooting went to school together."

While Stig had no known association with Stemler, Police allege that she was connected to Langi via "other associates".

Officers have alleged that Stig was part of a "greater criminal enterprise" and that she knew about the July 27 hit and helped the shooter before and after Stemler was gunned down.

"I wouldn't say (she was) a 'mastermind'," Inspector Gorman said in response to questions over the arrest earlier this week, "More like a lackey doing tasks."

Inspector Gorman said that there would likely be further arrests over Stemler's death, adding that Stig and Langi were not the only people who were allegedly involved.

Task Force Magnus was created in July to investigate six organised crime killings in Sydney in 2023, which Police say were all linked to the supply or importation of drugs into the city. Assistant Commissioner Michael Fitzgerald said the arrests are significant for the task force, adding that Magnus officers had successfully solved all the cases it was established to investigate.

"While the work is never truly done, this is a huge feat for our Command, who was given the difficult job of circuit-breaking the brazen violence we saw unfolding on our streets," he said.

"The safety of our wider community has - and always will be - our number one priority, and the people of NSW our motivation for crafting such a significant response, one that has evidently had noteworthy success."

Magnus' investigations are ongoing, Police said; anyone with information has been urged to contact CrimeStoppers online or via phone on 1800 333 000.