Robert Alan Gee, 44, of Stretton and Kristie Lee Willmot, 36, of Zillmere were arrested and charged over the death and had their cases mentioned at Beenleigh Magistrates Court on Thursday. Willmot is the baby’s mother.

Prosecutor Stephen Cochrane said five-week-old Michael Willmot sustained significant head trauma, rib and leg fractures, consistent with being shaken.

Police said paramedics responded to reports of an unresponsive baby at the park at Daisy Hill, south of Brisbane, on June 14 2021.

The child was taken to Logan Hospital where he was declared dead later that evening.

Police made the arrests after a 17-month probe into the baby’s death.

Detective Inspector Mark White said the boy died after suffering injuries from “significant force” which were not caused by an accident.

“All I can say is the medical examination of the child disclosed significant internal injuries,” he told reporters on Thursday.

“I actually won’t go into the details, it’s quite distressing.

“But it was quite clear, as at the end of that medical examination process, what the cause of death was.”

White said investigating the boy’s alleged murder had been challenging for his colleagues “to listen, to read this information and speak to people about it”.

White said despite the charges the case hadn’t been closed yet, and he called for any witnesses or people who visited or lived in the caravan park around June 14 last year to contact police.

“Caravan parks have people that come and go … maybe as as a resident, but also maybe visiting friends,” he said.

“If someone may have been in and around there and we weren’t aware of it at the time, if they could come forward, or someone may know these two people and may have had conversations with them, we’d be really interested to see what those conversations may have involved or articulated.”

Both accused were remanded in custody, with matter due to return to court on March 1.