Detective Inspector David Briese said the cause of death was undetermined and police were still waiting for autopsy results.
He said investigations were ongoing and urged anyone with information about the family to come forward.
“It’s being treated as suspicious and we’re running out all angles,” he said.
“We’ve obviously identified a number of family friends and associates who we’ve spoken to but no doubt there’ll be others out there that may know of the family and any circumstances surrounding the child’s death that we haven’t spoken to yet…”
Anyone with information is urged to visit Yamanto Police Station or call Policelink on 131 444.