UPDATE: Heat stroke has been confirmed as the cause of death of three-year-old Roanan James Joshua Philip Ace.
Detective Sergent Melonie Geck from the Maryborough Police District Child Protection and Investigation unit released the findings on Thursday afternoon and said police could make no further comment.
The child was found unconscious at about 3pm on Tuesday by his parents in the family's car.
He was taken to the Maryborough hospital, where several attempts to resuscitate him were made before he died.
Chris Foley, former State Member of Maryborough and Grace Community Church leader is the family's spokesman.
Mr Foley said he believed the family were visiting a friend's house for the day and fell asleep after a long drive when the tragedy happened.
"Roanan went wandering around and obviously climbed into the car and then the parents woke up and couldn't find him," he said.
"They were looking frantically everywhere for him and then found him in the car."
He said Roanan's death was a tragic accident.
"That can happen to anybody, any time," he said.
Details of how you can honour Roanan's memory in Friday's Fraser Coast Chronicle.
EARLIER: Tragedy has struck twice for a Maryborough man whose three-year-old son died after locking himself in a car at a Tinana property on Tuesday.
Roanan James Joshua Philip Ace was found unconscious in the back seat of the car in 35 degree heat about 3.40pm.
He was rushed to Maryborough Hospital in a critical condition and later died.
His father, Danny Ace, named his son after Joshua James Foley, the three-year-old son of former Maryborough MP Chris Foley, after Mr Ace accidently struck the child while riding his motorbike 19 years ago when the child ran out into the road.
Joshua later died in hospital.
In 2011, Mr Foley and Mr Ace spoke to the Chronicle about the tragic accident and how it had impacted both their lives, with Mr Foley spiralling into depression after the loss of his son and Mr Ace turning to an outlaw motorcycle gang to cope with the grief and guilt he felt after the incident.
Mr Foley spoke of how he was able to support Mr Ace through his grief and even visited him in jail when he was convicted of assault.
At the time, Mr Ace told him he now understood how it felt to lose a son.
Mr Foley, who now works as a pastor, is counselling Mr Ace and Roanan's mother, Kristy-Lee, through their grief.