Ian Robert Turnbull's widow Robeena ordered to pay damages for murder of Glendon Turner near Moree in 2014

Turnbull shot and killed Tamworth man Glendon Turner, and took Robert Strange hostage at gunpoint, while they were working as compliance officers with the Office of Environment and Heritage (OEH), late on the afternoon of July 29, 2014.

Turnbull died in prison on March 29, 2017, a year after he was jailed for a maximum of 35 years for Mr Turner's murder on Talga Lane at Croppa Creek, near Moree, and detaining Mr Strange for advantage.

Mr Turner's partner, Alison McKenzie, and Mr Strange, launched legal proceedings in the NSW Supreme Court and both sued the estate of Turnbull for damages for the ordeal.

"Without admission of liability", Turnbull's wife, Robeena June Turnbull, and son, Grant Wesley Turnbull, as the executors of his estate, agreed to pay $2.5 million to Ms McKenzie, as well as her legal costs.

The executors agreed to separate Deeds of Settlement with Mr Strange and Ms McKenzie, and her two children with Mr Turner.

The estate failed to make the payment by a court order in June this year, and in a judgement handed down in the NSW Supreme Court, Justice Michael Walton reinstated the proceedings, ordering Mrs Turnbull to pay more than $237,145.98 in interest to Ms McKenzie.

Mr Strange first initiated his damages case against Turnbull in 2015 and has been awarded $1.75 million in damages.

Mrs Turnbull, through the estate, has also been ordered to pay more than $166,000 in interest as well as his legal costs, after failing to settle the case before the June deadline with the sale of properties.

At the time of sentencing in 2016, Justice Peter Johnson said a minimum sentence of 24 years was needed because Mr Turner, was a public official carrying out his duties when he was fired upon.

Turnbull used a hunting rifle and fired several shots at Mr Turner, as he chased him around a car on the remote road reserve, telling him the only way he was leaving "was in a body bag".

He held Mr Strange hostage at gunpoint as he shot Mr Turner in the neck and chest and, after more than 20 minutes, fired the fatal shot into the 51-year-old OEH officer's back.

Turnbull then left and went home to see his wife one last time before he was arrested by Barwon police.

He was found guilty of murder by a jury after a five week trial

and pleaded guilty to detaining for advantage, which the court heard was triggered at his frustration over illegal land clearing prosecutions by the OEH.

In sentencing, Justice Johnson said he did not accept Turnbull had shown genuine remorse, but acted in "retaliation or revenge" as he hunted down Mr Turner, killing him in front of Mr Strange.

"The victim impact statement of Mr Strange confirms the terrifying and shattering nature of the ordeal to which he was subjected at the hands of the offender on 29 July, 2014," he said.

"Mr Strange did everything he could to try and save Mr Turner and to bring the incident to an end."