Scientific officers have not been able to establish the cause of death of a seven-year-old boy who was killed in a suspected double murder suicide.
Heavily pregnant Toowoomba woman Kris-Deann Sharpley, 27, her seven-year-old son Jackson, and her 52-year-old father Derek were found dead at a Biddeston property by a female relative on Monday evening.
While detectives have confirmed the two adults suffered close-range gunshot wounds to the head, the boy's cause of death remains unclear despite a post mortem examination.
Jackson was reportedly found tucked in bed with no visible injuries, while his mother's body was in the bathroom.
On Wednesday afternoon, preliminary pathology results had failed to shed any light on the matter.
Police have previously confirmed neighbours heard three shots on Sunday evening, but have stopped short of saying the incident was a murder-suicide.
Detective Inspector David Isherwood said police were considering whether another party was involved, but it appeared not to be the case.
The gun's owner is emerging as a key question.
On Tuesday, Det Insp Isherwood would not disclose anything about the firearm, apart from it being a "high-calibre weapon".
"As to whether it was owned by a resident of the house or by someone who is attached to the family or the house, we don't know," he said.
Heavily pregnant Toowoomba woman Kris-Deann Sharpley was found dead inside the home.
The deaths have shocked the Biddeston community.
Family friends have visited the home, which remains a crime scene, delivering soft toys and flowers.
"Never to be forgotten," read one note laid at the scene.
Family members have expressed disbelief that Mr Sharpley could have been responsible.
Ms Sharpley had moved to Biddeston to care for her father after the death of her mother in 2011.
Det Insp Isherwood confirmed the family was known to police.
Morning news break – March 5