A bomb that killed a man in New South Wales Central Tablelands was remotely detonated from a radio-controlled receiver, police say.

John Burrows, 58, was killed when an improvised explosive device (IED) detonated as he approached the garage of his mother's property at Portland, near Lithgow, in July 2015.

Police believe the Wallerawang power plant employee and greyhound trainer was the intended target of the device.

John Burrows, here with his wife Shirley, was killed by an explosive device. ( Fairfax Media: Wolter Peeters )

Months after the fatal explosion, police revealed the remains of the IED were concealed under a Hills 16-litre knapsack sprayer cardboard box.

Officers from Strike Force Avail said after extensive investigations it was believed a radio-controlled receiver and components of the device were likely sourced by someone in the Portland community.

The receiver, which was recovered at the scene, was a Spektrum brand AR610 owned and distributed by Horizon Hobby USA which is sold for use in planes, helicopters and other aircraft.

It is believed the product, which has only been available since May 2013, 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 have described the development as a "significant breakthrough" in the investigation.

"It was quite sophisticated — it was chilling, really, to think that a remote-controlled bomb was used to kill someone. It just doesn't happen," said Detective Chief Inspector Luke Rankin.

"From what I'm aware it hasn't happened in Australia in the last 30 years or so. It's a unique crime we've been investigating and one we're determined to get to the bottom of."

A metal plate found as part of the IED that killed Portland local John Burrows two years ago. ( Supplied: NSW Police )

He said information from the local community was needed as it was believed the bomb was likely sourced locally.

"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."

Strike Force detectives are confident there are people in the community who have information but 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," Chief Inspector Rankin said.

He said Mr Burrows had previous conflicts, which police were investigating.

"With John he was a family man, a working man, he lived a quiet life in Portland surrounded by his family. On the morning he was killed he was just going to collect his car from his mother's garage to drive to work," he said.

"So we have looked at potential conflicts he was involved in, but he certainly wasn't someone who was involved in crime."