But a dispute over money for an almost worthless car created a "history of animosity" between Jack Vincent Colless and Jack Henderson that ultimately led to one man being stabbed to death and the other being charged with his murder, Newcastle Supreme Court has heard.

Mr Colless, now 21, is accused of stabbing Mr Henderson, 20, once in the chest during a fight outside Mr Colless's John Street home at Cessnock on Anzac Day, 2014.

The stab wound penetrated Mr Henderson's left ventricle, causing him to bleed to death, the court heard.

Mr Colless on Tuesday pleaded not guilty to murder, the alternative count of manslaughter and the reckless wounding of Mr Henderson's friend, Ty Flood.

In his opening address, Crown prosecutor Brendan Campbell told the jury the pair had been mates at school, but their friendship had soured after a dispute between Mr Colless and the Flood family about a used car.

"They both lived in Cessnock," Mr Campbell said.

"They had been friends growing up.

"As had Ty Flood, he was friends with both of them.

"But you will hear that the relationship between Mr Henderson and Mr Flood on one hand and the accused on the other soured before this incident over a car.

"Mr Flood will tell you that he had sold this car to the accused.

"But the accused had not paid for it as he agreed.

"Others have a different take on that, including the accused in his interview with police.

"The point of that is that the accused considered it was a bone of contention between them and that the Floods and through them Mr Henderson were claiming money was owed and were harassing him about that.

"It is in that context that the accused in his interview said there was a group, that included Mr Henderson, that were harassing him.

"They were doing things like yelling abuse, threatening him, doing things to his car like throwing eggs and bottles.

"Very simply, it is the crown position that, even if those things occurred, it in no way justifies the accused stabbing Mr Henderson on the 25th of April."

There may have been hostility bubbling away under the surface, but the court heard the confrontation that led to Mr Henderson's death was a "coincidental meeting".

Mr Flood and Mr Henderson were visiting a friend's house in John Street when Mr Colless and his girlfriend arrived home next door.

Mr Campbell said Mr Flood had told police he did not know Mr Colless was living at the house.

Mr Henderson and Mr Colless exchanged words, then began fighting outside the home, the court heard.

What happened next is the subject of contention and a key issue in the murder trial.

But what is known that is when Mr Henderson got back into Mr Flood's car he quickly realised he was bleeding from a wound to his chest.

"I think you might have to take me to the hospital," Mr Henderson told Mr Flood, the court heard.

"I think he might have stabbed me."

Mr Henderson lifted his shirt to reveal blood was coming from his chest and running down his stomach, the court heard.

It was then that Mr Flood realised he too was bleeding from a cut to his elbow.

Mr Henderson was rushed to Cessnock District Hospital at 7.50pm.

Despite resuscitation efforts, including staff performing CPR for the next hour, he showed no signs of life and was declared dead about 9pm.

Mr Campbell said there were three witnesses to the fight outside the home in John Street.

But he anticipated none of them would tell the jury they saw Mr Colless stab Mr Henderson or even that they saw a knife.

"But the deceased was unquestionably stabbed," Mr Campbell said.

"[The witnesses] saw an altercation between the accused and Mr Henderson.

"The evidence that Mr Henderson was stabbed really comes from the medical evidence.

"The reality is that the wound that he had suffered simply was not survivable."

A forensic pathologist determined that cause of death was a single stab wound to the lower left chest, penetrating into the left ventricle of the heart at a depth of about five centimetres.

When police arrested Mr Colless later that night they found a knife with a five centimetre blade in his pocket.

"That knife has been tested and showed the blood of the deceased on the blade," Mr Campbell said.

"Now that blade was approx five centimetres, consistent with the knife, in essence, penetrating to the hilt."

When initially spoken to by police, Mr Colless could not believe Mr Henderson had died.

"I was involved, he can't be dead," Mr Colless told police outside his home, the court heard.

Later, when interviewed by police he said he had engaged in a fight with Mr Henderson in the hope of putting the long-running dispute to bed.

"He gave the version that he engaged in the altercation with Mr Henderson," Mr Campbell said.

"That at a point when he was on the ground, he had an open knife in his hand and that he made thrusting moves with that knife, but didn't think he got Mr Henderson.

"On his account he had the knife out because he was being assaulted by Mr Henderson and Mr Flood.

"Later on in the interview the accused said: "I was trying to defend myself in some way. I thought maybe getting it out would scare them away".

"That claim means you might have to consider the question of self defence.

"The crown says the accused could not have believed it was necessary to stab Mr Henderson, who was unarmed.

"Despite the history that had gone on between them.

"Secondly, what he did was not reasonable in the circumstances as the accused perceived them and that therefore self defence doesn't really arise in this case."

Mr Colless's barrister, Belinda Rigg SC, told the court her client's reaction after being arrested showed he had no intent to kill Mr Henderson.

"The most basic issue to be raised on behalf of the accused in a general sense is that he never wanted any of this to happen," Ms Rigg said.

"It is not in issue that the stab wound that tragically killed Mr Henderson occurred at a time when Mr Colless was holding the small pocket knife.

"But the defence will rely upon those things that he said to the police, showing that their wasn't the intent that is relied upon here by the crown.

"Rather they will be relied upon as demonstration as his lack of intent.

"Rather being filled with anguish confusion and despair for having contributed to the death of Mr Henderson."

Ms Rigg said the small knife was used by Mr Colless to skin rabbits while out on walks with his dog.

She said Mr Colless had not deliberately intended to stab Mr Henderson.

"There will be an issue of whether the crown evidence proves beyond reasonable doubt that the accused made a deliberate and conscious motion towards Mr Henderson while he had the knife in his hand," she said.

"It'll be the defence case that the knife wound was caused at a time when Mr Colless was on his back on the ground, being assaulted and that there was a lot of motion being exhibited by Mr Henderson towards the accused."

She said Mr Colless was scared of the men and the background between the parties contributed to his fearfulness as he lay on the ground during the fight outside his home.

"If the crown proves those very difficult propositions," Ms Rigg said.

"That is, that there was a deliberate motion of the accused that caused Mr Henderson's death and that the accused deliberately stabbed him to the chest with intent to kill or cause grievous bodily harm, then self defence is something that is raised."

The trial before Justice Richard Button continues.

The Newcastle Herald