The son of a convicted criminal brutally murdered in northern NSW has told a court his father died in a metal box with less dignity than an "animal in an abattoir".

James Falconer said at a NSW Supreme Court sentencing hearing on Friday that his father died with "no dignity, no respect and no mercy".

Terry Falconer was murdered while on work release from a Sydney prison in November 2001.

His dismembered body was found in plastic packaging bound with duct tape and wire on a bank of the Hastings River about 10 days after he disappeared.

Matthew Lawton, 42, and Anthony Perish, 41, were last year found guilty of murdering Falconer.

Perish's younger brother Andrew, 40, was found guilty of conspiring to murder him.

Falconer was transported unconscious inside a large metal box from Sydney to Girvan, north of Newcastle, where Lawton, Anthony Perish and a third man cut up his body.

Reading from a victim impact statement, Mr Falconer's son said his father had suffered worse than an "animal in an abattoir" and died "like a lion being pulled down by a pack of sniffing hyenas".

He said after being killed his father's teeth were pulled out with pliers and his body hung from a beam, before being dismembered.

"They gave him a terrible death," Mr Falconer said.

"He died slowly and painfully in that box."

James said he was haunted by dreams of the killing which took his "heart, mind and body to a dark place".

"I can't go any deeper into the pain they've caused," he said.

Lawton's counsel, Carolyn Davenport QC said Justice Derek Price should take into account the motive for the crime in sentencing her client.

She said the slaying stemmed from a belief that Falconer was responsible for the murder of the Perish brothers' grandparents, who were gunned down on their property at Leppington in Sydney's west in 1993.

Andrew Perish's lawyer, Winston Terracini, QC, said his client had a "well founded" and "honest belief" his grandparents were murdered by Falconer.

Crown prosecutor Paul Leask said the killing was unique because of the high degree of planning involved and it was carried out callously.

He said Andrew Perish had organised and paid for a boat in the lead-up to the killing and had numerous discussions about it, including one in which he said, "The c*** will be in pieces".

The three men will be sentenced on April 13.