Coroner Derek Lee found Turnbull – who was serving 35 years for the murder of Tamworth environment officer Glen Turner – died of acute kidney failure in a Sydney hospital in March last year.

In a coronial inquest in Glebe Coroner’s Court in Sydney on Wednesday morning, the court heard Turnbull died on March 27, 2017, at Prince of Wales in Randwick, seven days after being transferred to the emergency department by corrective officials.

Turnbull, then aged 82, had been in custody since the night he shot dead Mr Turner north of Moree in July 2014.

“The cause of Mr Turnbull’s death was acute kidney failure due to possible sepsis or cardiogenic shock, with congestive cardiac failure being a significant condition contributing to the death,” Mr Lee found, in a four-page report detailing the inquest findings.

“There is no evidence to indicate that any external factor contributed to Mr Turnbull’s death. Therefore, his death was due to natural causes.”

The court heard Turnbull attended a consultation with Justice Health staff on March 20 in prison where they noted “that he had difficulty swallowing and dyspnoea”.

From there, he was taken to the hospital’s emergency department and then later admitted with “septic shock and renal failure”.

The following day his condition deteriorated, and “a clinical decision was made to place Mr Turnbull on a palliative care pathway”.

“Mr Turnbull’s condition continued to decline over the following days. On 22 March 2017, Mr Turnbull’s family were advised of his prognosis and that his life expectancy was limited to the next few days,” Mr Lee found.

On March 27, two days after he was no longer verbally communicating or eating, his family visited him.

“During the visit Mr Turnbull ceased breathing and became unresponsive,” Mr Lee found. He died that afternoon.

In the inquest, Mr Lee said he had considered the available records from Corrective Services NSW as well as Justice Health and “cannot identify any matter associated with his care and treatment whilst in custody that contributed to his death”.

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Mr Lee found that Turnbull’s deteriorating condition was “due to natural disease process is well documented in the available medical records” and “appropriate clinical and administrative steps were taken to manage Mr Turnbull’s declining condition”.

“There is no evidence to suggest that the health care provided to Mr Turnbull whilst in custody was not within an expected standard of care,” he found. 

“There is no evidence to suggest that any act or omission by either CSNSW or Justice Health contributed to Mr Turnbull’s death in any way.”

In 2016, Turnbull was sentenced to a minimum of 24 years in jail for the "terrifying and shattering" murder of the Office of Environment and Heritage (OEH) compliance worker on a remote laneway, at Croppa Creek on July 29, 2014.

Turnbull confronted Mr Turner and Robert Strange, both Office of Environment and Heritage officers, and then shot Mr Turner in the neck. 

He then chased him around a car for at least 22 minutes and fired a number of shots before shooting Mr Turner in the back - the shot which proved fatal. Turnbull was arrested shortly after.