While the Office of Environment and Heritage has temporarily suspended operations around the crime scene at Croppa Creek, north of Moree, the department's chief executive, Terry Bailey, said there would be no let-up in enforcement.

But, as he spoke on Thursday, a bulldozer worked on multiple piles of felled trees that were set ablaze on a family property where the alleged killer, Ian Turnbull, 79, had cleared illegally.

Mr Bailey could not comment on this clearing operation but said surveillance work continued in the Croppa Creek area and that legal action against a local farmer was launched in the Land and Environment Court only five weeks ago.

Court records show that case, launched on June 25, involves Ian Turnbull and his grandson Cory. It is alleged they illegally cleared land on ''Strathdoon'', Cory Turnbull's farm, between January and September 2012.

Ian Turnbull has already pleaded guilty to using a bulldozer to clear 421 hectares on his son Grant's property, ''Colorado'', which is where piles of wood were being burnt on Thursday.

''Colorado'' is closer to the country road where Glen Turner, a 51-year-old father of two, was shot in the back on Tuesday evening.

A letter sent to Environment Minister Rob Stokes last month - from the Northern Inland Council for the Environment - complained that the government was failing to enforce the Native Vegetation Act against the Turnbull farms and said locals suspected political interference.

''As chief executive,'' Mr Bailey told Fairfax Media, ''I can assure you that I make all decisions and that there has been no political interference.''

Mr Stokes and Mr Bailey travelled to Tamworth on Thursday to meet Mr Turner's grieving family and colleagues.

''We are not conducting operational activities at the moment,'' Mr Bailey said. ''We need time for our staff to understand and digest.''

Mr Bailey said investigative work was continuing but would be reviewed internally before staff were allowed back at Croppa Creek.

''I'm confident our policies and procedures will continue to stand us in good stead but we will be, in the interim, reviewing those and I've asked some people to look at that immediately,'' Mr Bailey said.

When questioned about the tensions in the Croppa Creek area over illegal land clearing, Mr Stokes said: ''There has been a long history in relation to compliance in the Croppa Creek area.''

The minister did not read a letter warning of rising tensions but it was referred to the department boss, who responded to it, Mr Bailey said.

Ecologist Phil Spark, who has written to the government about illegal clearing at Croppa Creek, said authorities could have stopped the clearing long ago.

''These investigations have been going on for a long time,'' he said. ''This delay, and inaction, it has cost a man his life.''