Wheat farmer Ian Turnbull ambushed Glen Turner on a public road and opened fire while the environment compliance officer was inspecting an unrelated site, police will allege.
Mr Turner was not on the Turnbull family's properties and was not serving a notice for illegal land clearing when he was allegedly shot several times, throwing serious doubt on claims by Mr Turnbull's family that the 79-year-old farmer had been pushed to the edge by repeated harassment.
Detective Inspector Gavin Rattenbury said police will allege Mr Turner and a colleague from the Office of Environment and Heritage (OEH) were carrying out unrelated duties on the side of Talga Lane, near Moree, last Tuesday evening when Mr Turnbull allegedly pulled up beside them, armed himself with a rifle and opened fire.
A bullet in the back killed Mr Turner but it is understood that more than one shot hit the 51-year-old father-of-two. Mr Turnbull then drove home, where he was arrested four hours later.
After several reports last week that the OEH workers had arrived, unannounced, on Mr Turnbull's Croppa Creek property to serve a notice for illegal vegetation clearing, his family painted a picture of an elderly man constantly targeted by an aggressive government about clearing his land.
The incident generated widespread debate on native vegetation legislation, and came after years of mounting tension between farmers, environmentalists and governments about landowners' rights to clear vegetation for cropping.
Moree Plains Shire Council mayor Katrina Humphries said violence was "always going to happen". Federal Agriculture Minister Barnaby Joyce said: “You have this crazy situation where you don’t own the vegetation on your land, the state government does, and many people have had enough."
Last week, Mr Turnbull's family told News Corp that inspectors were constantly on their property and the farmer objected to the way the rules were administered by local authorities.
However, Fairfax Media can reveal that Mr Turnbull drove to Talga Lane, unannounced, about 5.40pm, while the compliance officers were working on the side of the road on a separate project.
Detective Inspector Rattenbury said it was not yet known why Mr Turnbull drove to Talga Lane, or why he stopped. Mr Turnbull's son Grant did not respond to Fairfax Media's requests for comment.
Mr Turnbull had never put in a formal application for land conversion and had been investigated and prosecuted several times for illegal clearing around Croppa Creek, an area that includes koala habitat.
In April, Grant Turnbull, who owns a neighbouring property, Colorado, withdrew his sole application for converting grazing land to cropping land.
An OEH spokesman said: "We can confirm Glen was not issuing a compliance notice at the time, nor was he on Mr Turnbull’s property."
Public Service Association of NSW assistant general secretary Steve Turner called on the government to carry out "serious risk assessments" of each frontline role, to ensure the safety of environmental compliance officers.
The OEH said the agency follows procedures beforevisiting remote properties to check if anyone there has a police history.
"OEH has a memorandum of understanding with the NSW Police force, which includes an agreement for the NSW Police force to provide OEH with information on criminal history, where required, for investigations under our legislation," a spokesman said.
Mr Turnbull will reappear in Moree Local Court on Tuesday. He has yet to enter a plea.