The nine-year-old was injured after a dog – which lived at a property on the riverbank near where the horrific incident took place – intervened. The boy's five-year-old brother was found dead in the river. Their 26-year-old mother, from Deniliquin, has been charged with murder and attempted murder.

The boy has suffered post-traumatic stress disorder in hospital since the incident in March. Neither he, his brother nor their mother can be named for legal reasons.

The mother was remanded until July in a brief hearing at the Deniliquin Local Court on Tuesday. She did not appear on videolink from jail in Junee and her legal aid lawyer told the court she also faced a charge of possessing two grams of cannabis. 

The two young boys had been in the care of their grandparents, but their mother was able to get access to them despite intervention orders aiming to prevent that access being in place.

After being released from jail on aggravated burglary charges, police will allege, she travelled to where the children were living, stayed in a caravan on the property, and a month later took them to the river.

The NSW Premier's office is investigating how it was allowed to happen, with a particular focus on the Department of Family and Community Services and Corrective Services.

It is understood internal government reviews have been completed but they have not been released.