Three men accused of being part of a “kill crew” have been charged after a mother was brutally kidnapped and murdered.

The body of Thi Kim Tran, 45, was found in a burned-out car in Beverly Hills in Sydney’s south-west on April 17.

Investigators allege her husband was involved with an organised crime gang in Melbourne. When the three men couldn’t find him, they instead killed Tran and injured their son, eight, by beating him with a baseball bat.

The incident began when police were called to a home in Bankstown after reports of a kidnapping. They were told a group of people armed with a firearm had pushed their way in and assaulted the boy before forcing the woman into a car.

About an hour later, the car was found ablaze in Beverly Hills with Tran’s body inside.

“Police will allege in court the men were part of a ‘kill crew’, tasked with finding and killing Tran’s husband,” NSW Police said on Friday.

“When they couldn’t find him, [they] murdered Tran and injured their son.”

The men – aged 20, 21 and 32 – have each been charged with murder and other offences, including conspire and agree to murder any person.

A fourth man, Anh Nguyen, 29, was charged in August with murder and wounding with intent to cause grievous bodily harm over the attack police and remains before the court.

The boy who was beaten with the bat suffered head injuries and was treated in hospital. A 15-year-old boy who was also at the Bankstown home was uninjured.

-AAP