Delivering herinquest findings on Tuesday,deputy state coroner Jane Bentley concluded that the Child Safety Department"failed in its duty"to protect the young boy.
Opposition leader Deb Frecklington described the case as"horrific"and one that"no Queenslander could ever,ever stand by".
"This was someone who was known to the child protection system in Queensland – it is a massive failure of the child safety system under Annastacia Palaszczuk,"she said.
LNP child safety spokesperson Stephen Bennett said the system needed an"overhaul",with adoption an option that should be considered for children in situations such as Mason's.
Both Child Safety Minister Di Farmer and the department have been contacted for comment.
Speaking at a press conference in Townsville as the findings were handed down,Premier Annastacia Palaszczuk said that once she saw the report,the government would be"acting swiftly"to implement any recommendations.
Psychologist and child development expert Dr Katrina Lines,speaking on behalf of Act for Kids,said the report was"heartbreaking"to read.