Meanwhile, searchers continue to comb the Murray River in Moama, on the border of NSW and Victoria, today looking for the missing 5-year-old.
Marine Rescue NSW, Echuca Moama Search and Rescue, Victoria Police and the SES assisted in the search.
Emergency services at the scene this morning.
Her aunt said the Department of Human Services, police and corrections authorities "have a lot to answer for" in how the tragedy unfolded and why it wasn't prevented.
Police divers search the Murray River for the missing five-year-old after an alleged drowning attempt by his mother.
The mother then focused her attention on the five-year-old boy, taking him into the water and holding his head below the surface, the court heard. The community is. It's something someone has to do, we're the people, who are the ambulance, the fire brigade, we are people who need to do these things.
Detective Sergeant Swinton said the woman had told police of her intention to kill both children, and also allegedly told witnesses the night before that she "had to drown my babies".
The Deniliquin woman, aged in her 20s, was extradited from Victoria to New South Wales on Friday night and charged with the attempted murder of one of her sons.
The woman, who can not be named for legal reasons, did not appear before Deniliquin Local Court in southern NSW as expected on Saturday morning.
On Friday afternoon, she appeared by video link at an extradition hearing held in Bendigo, sobbing uncontrollably as Detective Sergeant Trent Swinton gave the magistrates' court a horrifying account of the events on Thursday night.
Fairfax Media understands the woman and the two children were all related.
Police divers were called in on Friday morning to search for a fiver-year-old boy who is feared drowned
"The dog is four years old and it's never attacked one person, has grown up with kids, and it's always been around kids playing", she said.
It follows police being called to Perricooota Road, Moama, at 7pm on Thursday where a nine-year-old boy was found with serious dog bite injuries.
He told reporters that the case was "just bad", before going on to say that "it will rock the community of Australia".
The mother, who did not apply for bail, has been remanded in custody.
Her photo was published in a local newspaper as part of an operation cracking down on wanted criminals.
Later the mother, 27, presented herself to police at Echuca in Victoria about 10pm and was taken to Echuca Hospital to get treatment for a dog bite.
The youngest boy's body was found by police divers who scoured the rivers, near Moama in southern New South Wales, late this morning. "The actual circumstances are unknown", Supt Condon said.
The pitbull, named buddy, was credited with helping rescue the nine-year-old after biting his mum and allegedly helping to drag the boy out of the water, his unnamed owners said.
"He required some surgery on the dog bites at this stage and, of course, he is distressed".
It's a tragic story, not only for the community, the police, especially the family.
"I think it will rock the community of Australia", he said.