Anh Nguyen, 29, faced court on Friday charged with murder and wounding with intent to cause grievous bodily harm over the attack police believe is linked to a "major player" in organised crime.
He did not apply for bail and remains in custody to face court again in November.
Police allege Nguyen facilitated the gunpoint abduction of the woman, aged 45, from her Bankstown home in Sydney's southwest in front of her two sons, aged eight and 15.
The younger boy was hit with a baseball bat during the April attack.
The mother's body was found in a torched car about an hour after the alleged abduction.
The shocking crime was believed to stem from a dispute between the woman's de facto husband and an interstate organised crime group he allegedly worked for.
Police have previously said the mother and sons subject to the "callous, brutal" attacks were innocent people - unaware their father had a link to an organised crime group.
That crime group had "muscle for hire" carry out the kidnapping and murder, police said on Friday.
"They've been contracted by someone part of that organisation," NSW Police Detective Superintendent Joseph Doueihi told reporters on Friday.
The woman had no criminal record, while her partner was known to police for minor drug matters.
He has not yet been charged with any offences.
"If there was evidence developed at a later stage that he was involved in drug activity, we may consider that," Det Supt Doueihi said.
"But at this particular stage, the priority is to investigate the homicide.
"We treat that person (the husband) as a witness to the homicide."
Nguyen was previously known to police but they were "not significant matters".
He is believed to be a "very close associate" of the woman's partner.
Both men are believed to be linked to a Victorian drug syndicate considered a "major player" in Australia and likely overseas, police said.
"They're responsible for the manufacture of large quantities of methylamphetamine, the importation and the distribution of those drugs," Det Supt Doueihi said.
The eight-year-old boy needed emergency surgery for serious head injuries and was in an induced coma for days following the attack.
He is still receiving ongoing treatment.
"Remarkably, he has made a quick, good recovery and hopefully he'll get back to his normal life," Det Supt Doueihi said.
The older sibling witnessed his mother's abduction, suffering psychological injuries.
Investigations are continuing as police look for others allegedly involved in the woman's murder.
