Police are urging that same community to help them put together the final pieces of the puzzle surrounding the death of the popular 58-year-old father of three.

Investigators have determined that the improvised explosive device (IED) which killed Mr Burrows early on the morning of July 24, 2015 was detonated remotely with a radio-controlled receiver.

Chifley Local Area Command crime manager, Detective Chief Inspector Luke Rankin, said someone in the small community of 2000 people near Lithgow must have information about the origin of the radio-controlled receiver. 

"We are particularly interested in speaking to retailers or people in the Portland area who may have sold an item – on social media sites, garage sales or even disposed of at a local tip – matching the description of the radio-controlled receiver," he said.

"We believe the steel tubing used around the outside of the device was sourced as scrap metal and modified to make the device."

Detectives are confident there are people with information about Mr Burrows' death but, for whatever reason, have been reluctant to come forward.

"Someone must know something about these devices so I urge you to pick up the phone and call us – you can do this anonymously through Crime Stoppers," he said.

The death of Mr Burrows, an employee at the local power plant for three decades, left the community reeling.

He was killed at 6.30am on a Friday when, as part of his regular morning routine, he walked from his home on Wolgan Street to a garage behind his mother's home on nearby Villiers Street.

As he reached the roller door of the garage, he bent over to examine a Hills brand 16 litre knapsack sprayer.

The sprayer concealed the IED which exploded in Mr Burrows' face, killing him instantly.

After a lengthy investigation, police believe the radio-controlled receiver and components used to make the device were most likely to have been sourced by someone in the Portland community.

Police recovered the radio-controlled receiver, described as a Spektrum​ brand AR610. The brand is owned and distributed by Horizon Hobby USA and sold for use in planes, helicopters and other aircraft.

The product has only been available since May 2013 and could have been purchased on its own or sold inside a product such as a ready-to-fly model aircraft kit or helicopter kit, police said.

At the time of his death, Mr Burrows' brother Garry Burrows remembered him as a good man.

"We never ever dreamt it would come to this," he said. "He was one of the best, truly one of the best."

Police are urging anyone with information in relation to this incident to call Crime Stoppers on 1800 333 000.