Prosecutors have called for the man who murdered three neighbours on their rural properties to never be released from prison, despite him entering guilty pleas.

But a lawyer for Ian Francis Jamieson has urged a Supreme Court judge to give the killer a "glimmer of hope" for rehabilitation and set a minimum term to acknowledge his pleas, even if it meant he might not get parole until his mid 90s.

Jamieson, 65, repeatedly stabbed Greg Holmes, 48, on the night of October 22, 2014, before arming himself with shotguns and driving to another property, where he shot Mr Holmes' mother, Mary Lockhart, 75, and her husband, Peter Lockhart, 78.

The use of a dirt track between the Wedderburn properties of Jamieson and Mr Holmes was a source of contention between them.

Jamieson pleaded guilty to murdering the Lockharts and did the same over Mr Holmes' death, but then tried to fight the first charge, by arguing he killed the younger man in self-defence, and then received bad legal advice.

Justice Elizabeth Hollingworth this month refused the application, which meant Jamieson pleaded guilty to all three counts of murder.

Pleading guilty normally earns offenders a significant discount in sentencing, but prosecutor Andrew Tinney, SC, told the court on Wednesday Jamieson should never be given the chance to get parole.

Mr Tinney said Jamieson's bid to change his plea had prolonged the distress among the victims' family and friends, and that the claim Mr Holmes stabbed him with a syringe was a "complete fabrication".

Even withstanding there had not been a trial, Jamieson's crimes were "depraved and despicable and deserving of the court's strongest condemnation", the prosecutor said.

Jamieson was intent on confronting Mr Holmes when he went to his neighbour's property with a hunting knife, the court heard.

After that attack, he went home to get two shotguns, went to the Lockharts' home and shot the couple, reloading to inflict post-death wounds.

"He left behind a scene of absolute horror and depravity, the likes of which would rarely be seen," Mr Tinney said.

Defence counsel John Desmond said Jamieson had called triple-zero to report his crimes, had co-operated with police and deserved some discount for pleading guilty and for his deteriorating mental ealth.

There was a public interest in encouraging prisoners to admit crimes, he said, and life without parole would mean Jamieson wouldn't get that credit.

"If, if, Jamieson is still alive and if he was ever paroled in these uncertain times, given the lack of relevant prior offending ... his prospects for rehabilitation should be found to be reasonable," Mr Desmond said.

After the killings, the court heard, Jamieson went home and told his wife, called triple-zero and then telephoned friends.

He asked one to come and care for his wife, because "I will never see the light of day".

Later, he told police: "I mean there's no excuse for doing what I did, I know that. But it was time I put an end to it and that's what I did."

Justice Hollingworth said Jamieson had not shown a "skerrick of remorse".

The father of three has been in custody almost 640 days and will be sentenced on Friday.