Detectives investigating the death of toddler Kamahl Bamblett in NSW's Riverina region now believe he was murdered by someone known to the family.

Key points: An autopsy since revealed the 14-month-old died from significant injuries to his abdomen

An autopsy since revealed the 14-month-old died from significant injuries to his abdomen Police said if the child was given treatment, there was possibility he would still be alive

Police said if the child was given treatment, there was possibility he would still be alive Kamahl's extended family have started a campaign for justice

When police were called to the family's Wagga Wagga home at 10:45am on January 13, the family told officers the 14-month-old died from a spider bite.

But an autopsy since revealed the young boy instead died from significant injuries to his abdomen.

Police were unable to say whether a weapon was used, but they believe Kamahl was likely bashed to death inside the Wagga Wagga property.

Detective chief inspector Andrew Spliet said Kamahl was robbed of his chance to survive.

"The cause of death was blunt force trauma to the abdomen area," he said.

"We believe a person or persons is responsible for those injuries to the child.

"It's likely that if an injury had occurred and the child was given some form of treatment, there's a possibility that the child would still be alive now."

The toddler's mother, Tonnisha Sebbens, and her boyfriend Emmett Brown, were at home on the night of the toddler's death.

"You'd expect that a 14-month-old child would be safe in their home," detective Spliet said.

Police believe several people came and went from the home that night — some of whom remained persons of interest.

"It's simply not a matter that goes away — we will continue to investigate this matter until we get a result," Detective Chief Inspector Spliet said.

Carla Sebbens with baby Kamahl, who she described as a "beautiful little boy". ( Supplied )

#justiceforkamahl campaign

Extended family and friends of the toddler have been campaigning for justice, saying they do not believe he died from a spider bite.

Carla Sebbens spent many days with Kamahl when he was in his grandmother's care and has started a social media campaign #justiceforkamahl.

"I just wanted him to live on forever, he was a beautiful little boy," she said

"He was a kid full of love, a kid full of joy and he lived for dancing.

"This should never have taken place, this should never have happened, this boy should still be here."

Ms Sebbens said the answers were out there.

"If anybody knows anything please come forward, please," he said.

"Because I know a lot of people would like answers, me and my children would like answers, it was a part of us just as much as anybody else."