The verdicts were entered by a jury in the NSW Supreme Court at Queanbeyan on Tuesday morning, following roughly a week of deliberations in the trial of 20-year-old Daniel James Sharpe.

Sharpe, who was only 18 at the time of the incident, admitted stabbing 29-year-old Andrew Drake 11 times in Surfside, just north of Batemans Bay, in April 2019.

But he claimed it was not murder and that his actions were reasonable and necessary to defend his father David Sharpe against an attack perpetrated by Mr Drake.

The jury heard during the trial that Daniel Sharpe had been in a shed with his dad when Mr Drake and sister Penny Drake hopped over the fence from an adjoining home to listen to music and socialise with them.

It was not in dispute that things were amicable until David Sharpe "chastised" his son for breaking a glass, prompting Ms Drake to take the then-teenager aside to check he was OK.

While those two were talking outside the shed, they heard raised voices and stepped back in to find David Sharpe and Mr Drake fighting.

What happened next was the focus of the trial, with David Sharpe unable to recall what had happened because he had been so drunk and Ms Drake also unclear after being hit in the face and "blacking out" as she tried to break the altercation up.

Lawyers on opposite sides of the case advanced different versions of events.

Crown prosecutor Kate Ratcliffe told the jury that David Sharpe and Mr Drake were having nothing more than a minor push-and-shove when Daniel Sharpe violently intervened.

She said the younger Sharpe had repeatedly "plunged" a knife into Mr Drake, with no possible belief that what he was doing was reasonable and necessary to protect his father against an unarmed man.

Ms Ratcliffe claimed Daniel Sharpe, having just been "humiliated", murdered Mr Drake to prove to his dad that he could fight and that he was "not a little kid".

She said that in the process of stabbing Mr Drake, the accused had accidentally slashed his father's hand with the knife.

But defence barrister Troy Anderson told the jury that during the early stages of the fight, Mr Drake was in fact armed with the weapon.

He said his client had seen Mr Drake raise the knife and "slash", slicing David Sharpe's hand with it.

Mr Anderson claimed Daniel Sharpe had then inserted himself into the altercation, grabbing Mr Drake's arm and twisting the knife back into the 29-year-old.

He said Daniel Sharpe had ultimately gained control of the weapon and used it to inflict the remaining wounds as Mr Drake continued to fight and pose a credible threat.

While Daniel Sharpe was charged only with murder, the possibility of instead finding an accused person guilty of manslaughter must be left to juries in NSW where such a verdict is "open on the evidence".

That was the case in this trial, with the jury of 11 ultimately clearing Daniel Sharpe of murder but convicting him of the less serious offence.

The offender has been remanded in custody to await sentencing in April.