An independent review will examine whether the alleged murder of a four-year-old boy at the hands of his mother could have been prevented.

The 32-year-old woman has been charged with murder after the “extremely confronting” discovery of the boy’s body inside a Wyong home, on the NSW Central Coast, on Saturday afternoon.

Authorities will investigate the circumstances surrounding the death, including whether child protection officers were aware of the family, who was involved in the boy’s care and what could have been done to prevent his death.

NSW Families Minister Kate Washington was expected to announce an independent review into the death on Monday afternoon.

Welfare concerns were first raised after the woman took herself to the local police station on Saturday and spoke with officers, Superintendent Chad Gillies said.

“Through those conversations, police formed genuine concerns and that’s what triggered our response,” he said on Sunday.

“It was an extremely confronting scene.”

The ABC is reporting that court documents show police obtained an urgent court order to forensically examine the woman’s mouth, ahead of charges being laid.

The order allowed them to take samples of the woman’s internal mouth contents and forensic material, as well as a buccal swab to collect DNA. It also allowed them to obtain samples of the woman’s nails and material from under her nails.

The boy had significant arm injuries. Police are yet to confirm his cause of death.

Investigators believe he lived alone at the unit with the woman.

She was known to police and detectives were not looking for anyone else in relation to the boy’s death, Gillies said.

It is also unclear whether the boy had been deceased for several days.

The NSW Department of Communities and Justice said it had previously had contact with the family and would examine all relevant information.

“Given the matter remains the subject of an active NSW Police investigation, it would not be appropriate to comment further at this stage,” a spokesperson said.

The mother was charged on Sunday with domestic violence-related murder.

Among items seized from the pair’s Wyong home for forensic testing were the that the woman used to drive to the police station.

“Whenever a child is [allegedly] a victim of violent crime and whenever a child is murdered, it strikes at the core of community. That’s why it’s absolutely important we work through this methodically, we try to understand what’s happened, why it happened,” Gillies said on Sunday.

“From my perspective, we owe that to that little boy to make sure that we get the exact circumstances and present them to the court in due course, and that is the focus over the coming days and weeks for investigators.”

Tributes including stuffed toys and flowers were placed outside the boy’s home on Monday, as shocked locals reacted to the incident.

“Now is a really tough time for family and the local community of Wyong, but that’s why it’s absolutely imperative that our police pull together and make sure that we do the absolute best job we can in really difficult circumstances,” Gillies said.

The woman’s lawyer Neusha Ghahreman did not apply for bail on behalf of her client, who did not appear in court during a brief hearing on Sunday.

The case was adjourned until September 1.

Lifeline 131 114

Kids Helpline 1800 55 1800 (for people aged 5 to 25)

beyondblue 1300 224 636

-with AAP