Three people have been charged over the death of 21-month-old Mason Jet Lee north of Brisbane last month.
The boy’s body was found at a Caboolture home on June 11.
The child had suffered traumatic injuries in the days before his death.
Detective Inspector Paul Schmidt said the cause of death was peritonitis, brought on by a ruptured duodenum, which is the first part of the small intestine.
Peritonitis is usually the result of a fungal or bacterial infection caused by an abdominal injury or an underlying medical condition.
Detective Inspector Schmidt said the trio has been accused of failing to provide care for the toddler, but it was not clear who inflicted the boy’s injuries.
“The injuries sustained by the child would’ve been obvious, would’ve been deteriorating, and would’ve been significant over a period of time leading up to his death,” he said.
A 27-year-old woman from Caboolture South has been charged with manslaughter and is due to appear in Toowoomba Magistrates Court later today.
William Andrew O’Sullivan, 35, and Ryan Barry Hodson, 17, have been charged with manslaughter.
O’Sullivan did not apply for bail during a brief appearance in Brisbane’s Magistrates Court.
He was remanded in custody, with his case adjourned to August 8.
Hodson appeared in Caboolture Magistrates Court where his case was adjourned until Monday, when he is expected to apply for bail.