The body of a five-year-old son was found in the Murray River at Moama, the police have confirmed.
Divers discovered the body about 11.35am on Saturday.
His body is yet to be formally identified but police believe it to be that of the five-year-old son of a 27-year-old woman who is alleged to have tried to drown both her sons on Thursday.
The boy's nine-year-old brother is in a stable condition at the Royal Children's Hospital in Melbourne.
NSW Police on Saturday upgraded the charge against the 27-year-old woman to attempted murder.
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The mother faces one charge of attempted murder relating to the nine-year-old and did not attend her scheduled court hearing at Deniliquin Local Court on Saturday morning.
Another charge is expected to be filed, police say.
The 27-year-old turned herself in to police in Echuca, on the NSW-Victoria border, on Thursday night after she was apparently attacked by a dog at the scene of the incident.
The woman's older son, aged nine, was also mauled and was taken to hospital but authorities spent Friday scouring the river for the younger boy, aged five, but couldn't find him.
Police divers scouring the river will be assisted by Marine Rescue NSW, Echuca Moama Search and Rescue and the SES on Saturday.
The boy's mother was released from jail a month ago.
NSW police have said further charges relating to the five-year-old will depend on the result of the search.
The nine-year-old son is in hospital in Melbourne after also suffering serious dog bites on Thursday evening.
Fairfax Media reports 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".
