Baseballs embedded with screws were inside an improvised explosive device that killed a greyhound racing trainer in central western NSW, a court has heard.
John Burrows, 58, died after a bomb detonated as he approached his mother's garage in Portland, near Lithgow, in July 2015.
Paul John Fitzpatrick, 70, was charged with his murder and is facing trial in the Supreme Court in Bathurst.
In week three of the four-week trial, the court heard from improvised explosive device (IED) expert Christopher Page from the Australian Federal Police.
Mr Page said in all his years analysing bombs, he had "never encountered the use of baseballs in an IED".
The heat-damaged balls were shown to the court, along with two metal tubes that made up part of the explosive device.
The court also heard parts of the explosive device's batteries were found in Mr Burrows body, something consistent with "directional fragmentation".
He said directional fragmentation created a "shot-gun effect".
"[The bomb had] screws, a baseball and [then] a power source [coming] out through the top," Mr Page said.
Mr Page said he had seen "similar" types of bombs in South-East Asia and Afghanistan.
He said a degree of technical knowledge was needed to build the device.
The explosives expert said he could not say with confidence whether the bomb was detonated by a radio-controlled device, even though a receiver was found at the scene.
He said he believed the device was hidden in a cardboard box.
"[It] would allow the person to inspect the box at close range," he said.
Police also told the court documents containing bomb-making information were found in the accused's bedroom.
Mr Burrows and Mr Fitzpatrick had been in a serious fight in 2011 in which Mr Fitzpatrick suffered fractured cheek bones and required surgery, the court heard.
Mr Burrows was a Wallerawang power plant employee as well as a greyhound racing trainer.
The trial continues.
