"The body is yet to be formally identified, but is believed to be that of the five-year-old."
The mother, 27, who can't be identified for legal reasons, was yesterday charged with attempted murder of her nine-year-old son.
She appeared before Deniliquin Local Court earlier today in relation to the nine-year old boy's injuries. She was refused bail but will reappear via audiovisual link, at Deniliquin Local Court on Monday. A NSW Police spokesperson said further charges are expected to be laid at that time
Police alleged the woman took her children to the Murray River and told her eldest son, 9, to get into water before she tried to drown him.
Detective Sergeant Trent Swinton told the court the younger son, 5, was screaming during the incident. The older boy managed to struggle free when the woman turned to the younger boy. He was last seen drifting facedown in the water.
After escaping from his mum, the older boy was "savagely mauled" by a dog.
Screams were heard by people on the riverbank but they did not witness the incident, the court was told on Friday.
The nine year old boy who survived the attack was later taken to the Royal Childrens' Hospital in Melbourne where he remained in a serious but stable condition this morning.
His mother turned herself in to police in Echuca, on the NSW-Victoria border, on Thursday night after she was allegedly also attacked by a dog at the scene of the incident.
Outside court this morning, her lawyer Peter Hebbard said his client was distressed. "She's confused and she's upset," he told reporters.
"She didn't ask for bail, she told me 'she knows there are serious matters, and I'm not going to make a bail application'." Mr Hebbard said it was too early to say if his client plans to fight the charge against her.
"She has apparently made admissions, according to police," he said. "At this stage she certainly hasn't given me instructions about which way she's going to plead."
Earlier, Fairfax Media reported the woman appeared via video-link in a Bendigo court on Friday where a detective said she'd "made full admissions about her role and told police of her 'intention to kill both children'".
The court also heard she had allegedly told witnesses she "had to drown my babies".
The children had been living with their grandmother for more than a year. The grandmother's lawyer, Dale Brooks, said he had made "considerable representations" to both Family and Children's Services and Corrective Services about the "imminent risk" to the boys.
He described the response as "absolutely nil".
In a letter to the authorities on Thursday, Mr Brooks made serious allegations against the department and warned of a potential claim of negligence.
He said his client was told she would have to "put up" with her daughter living at her house until alternative arrangements were made.
The daughter then "snatched" the children in the grandmother's car.
Mr Brooks said his client blamed authorities for the tragedy because they had essentially "off-loaded" the woman, further exposing the grandmother to violence and physical harm.
"It's an appallingly sad country town saga," Mr Brooks said.
Police said a search for the younger boy was suspended in fading light overnight but had resumed Saturday morning before his body was located.
- With AAP
