A shearer who claims to have no memory of murdering his father and uncle at the family sheep farm in central Victoria has been jailed for 34 years.
VIDEO: Listen to Justice Lex Lasry sentence Ross Streeter below.
Supreme Court Justice Lex Lasry described the murders of Ross Streeter's father and uncle as "an extraordinary case" given he appeared to have had no motive.
"Your actions have shattered the lives of those around you," Justice Lasry told Streeter when jailing him for 34 years with a non-parole period of 25 years.
"There is an air of desperate disbelief that you could have done what you did.
"A contented rural life has been all but destroyed for your family as a result of these events."
Justice Lasry had been due to sentence Streeter in December but decided to wait for a second psychiatric report to try to find an explanation for Streeter's actions.
The judge had been troubled by Streeter's claims that he had no memory of the shootings.
The first report, by psychiatrist Dr Lester Walton, revealed Streeter claimed he had "a patchy recollection at best for the day in question and no specific memory of the actual killings apart from a few mental images of arguing with his father and then shooting him".
"He has no memory of the content of the argument, just a lot of yelling," Dr Walton said.
"I've never come across a case like this, a double killing with no explanation."Dr Lester Walton
He suspected "what's happening is that there are just so many brain processes occurring, things are whirring around when someone is so highly aroused, that the memory tracks are just not laid down and recalled".
"I've never come across a case like this, a double killing with no explanation."
Justice Lasry said a second psychiatric report by Dr Douglas Bell found Streeter was cognitively intact and his mental state normal.
"Dr Bell said you do not suffer from any anxiety disorder and you are not depressed.
"Dr Bell is clearly dubious about your claimed lack of memory of what occurred.
"He referred to what he described as your "purposeful execution of a plan to commit murder and then set up an alibi'.
"However, whether your claimed lack of memory is feigned as a protective measure seems ultimately to have relative little significance and it has had no effect on the sentence I will impose on you.
"The court and your family know what happened.
"On the more important issue of what drove you to do this, Dr Bell cannot offer an explanation and so it remains a mystery."
The judge said he was dubious about the genuineness of Streeter's claimed memory loss.
But he could not be satisfied beyond a reasonable doubt that that his memory loss was feigned.
"Your moral culpability for these offences is not diminished because you had no obvious motive for what you did."
Streeter, 31, pleaded guilty to murdering his father, Douglas, and uncle, John, on March 14 at the family's 1600ha Natte Yallock sheep farm, near Avoca, 200 kilometres north-west of Melbourne.
Streeter's father had been diagnosed with the fatal motor neurone disease in January last year and given one to five years to live. Streeter denied the shooting of his father was a mercy killing.
After first shooting his uncle and then his father a few minutes later, Streeter threw the shotgun and a number of cartridges into the farm dam before driving off.
When the bodies of the two men were found, Streeter was interviewed by homicide detectives and gave a detailed account of his movements on the day of the murders. He claimed not to have seen his father or uncle on the day.
On Saturday, March 16, Streeter sent a text message to his brother Anthony saying, "I've gone to be with dad and Jack. I'm up at the old water tower on the hill. Sorry, but I have to go. Look after mum. I'm sorry for what I have done."
Ross Streeter told his uncle, "It was me", indicating he was responsible for the murders.