A man who fatally assaulted a pensioner and dropped his body from a window inside a surfboard bag, then plotted to kill a witness with a heroin overdose, must serve a "significant period in custody", a court has been told.
Mark Kenneth Jenkin, 47, was found guilty of manslaughter in June last year after he carried out at least two violent assaults on Mark Dower, 56, which left Mr Dower with broken ribs, a swallowed tooth and several fractures, including to his spine.
In a judge-alone trial in the NSW Supreme Court last year, Justice Peter Hamill found Jenkin failed to render medical assistance to Mr Dower after the March 2015 assaults, which breached a duty of care and contributed to his death.
Mr Dower's body was found in a shared laundry at a unit block in the Wollongong suburb of Mangerton on April 16, 2015 after a call was made to Crime Stoppers.
A woman, who cannot be named, gave evidence that she helped Jenkin move the body to the laundry, still encased in a surfboard bag, after it was dropped 5.5 metres to the ground from his unit.
While he was in custody, Jenkin plotted to kill the woman with a "hot shot" of heroin, which would cause an overdose. He was found guilty of conspiracy to murder over the plot, which unfolded in a phone call in August 2015.
On Friday, at a sentencing hearing for the two charges, Jenkin's barrister Gary Corr said his client started self-medicating after a traumatic childhood. He said "as part of the self-medication, it tends to be that people wind up in the criminal milieu".
Mr Corr said it is "inevitable" his client is going to get a lengthy sentence, but said special circumstances should be found which would allow Jenkin a longer period of supervision in the community when he is released.
"When he gets out, he will be in his 50s. He will have spent most of his life since his early 20s in custody," Mr Corr said. He added that when Jenkin is released he will be "well beyond the age where people do normally engage in violent criminal activity".
Crown prosecutor Michael Fox said Jenkin has a continuing propensity for violence and has been diagnosed with antisocial personality disorder and a "severe substance abuse disorder".
Speaking to a forensic psychiatrist on March 20, Jenkin said he was smoking Buprenorphine while in custody to numb himself, and sleeps up to five hours each night. When Mr Dower was mentioned, Jenkin said: "I'm sick of everyone calling him the victim, he just died".
Justice Hamill said he is not inclined to make a positive finding on Jenkin's prospects for rehabilitation.
"Mr Jenkin needs to serve a significant period in custody," Justice Hamill said.
In a victim impact statement by Mr Dower's daughter, dated November last year, she said her father was all she had left of her family and there were no words to describe the "pain and endless grief I have to carry for the rest of my life".
"The death of my father is a nightmare. It is a tragedy most people cannot even imagine," she said. "All I ask for is justice."
Jenkin will be sentenced on May 23.