Just days before his Supreme Court trial was due to begin, Dale Stone, 50, pleaded guilty to the December 2017 murder of Wayne Binse, 37.

The victim was the half-brother of crime figure Christopher "Badness" Binse, who infamously taunted police by sending them postcards while on the run, and shot at officers during a 44-hour siege.

The court was told Stone had an ongoing dispute with his neighbours because any vehicle parked outside their house impacted his ability to use his driveway.

Before the killing, Stone held his hand like a firearm and pretended to shoot, intimidating Mr Binse's partner, prosecutor Robyn Harper said.

On the day of the murder, Mr Binse and his partner arrived home to find the windows of their home broken.

Stone fired a round from his 12-gauge shotgun, which had been fitted with a silencer, and hit Mr Binse in the groin from a range of eight to 12 metres.

He walked closer to Mr Binse, laughing and shot his victim to the head from close range, asking: "Do you think you're smart now?".

Stone then called triple zero twice, the second time claiming another person had "driven by" and shot Mr Binse.

Stone later told police he had only discharged his firearm because two men had entered his front yard.

He didn't want to refer to the offence as a murder, but preferred "termination of an individual".

Ms Harper said Stone smashed his victim's windows to give credibility to his claim that the incident had been a drive-by shooting.

Mr Binse's other brother Barry read a statement to the court on Wednesday, saying it was "extremely difficult" watching their mother come to terms with the loss.

"My baby brother is gone," he said.

"We all wish he was here. This will reflect on us forever."

Stone's lawyer Richard Edney disputed the idea the killing was an "ambushed, premeditated murder".

He said Stone had increased his use of alcohol and cannabis and had become paranoid, "experiencing florid psychotic phenomena".

Before the killing, Stone had been assaulted by Mr Binse, Mr Edney said.

Ms Harper agreed there had been an assault, but disputed its severity, and argued the killing was "planned, premeditated, unprovoked".

"He lay in wait, shut the gates and broke the windows of the property," she said.

Justice Paul Coghlan said he needed to calculate the influence of Stone's mental illness on the crime.

Sentencing is expected in a few weeks.

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Australian Associated Press