Death or serious injury were intended when an teenaged girl walked up to a 54-year-old man and plunged a knife into his chest, a jury has been told.

The Crown has delivered its final argument in the trial of a 16-year-old and a 14-year-old accused of murdering Hamilton man Norman Kingi in a late night street confrontation.

The pair are on trial in the High Court in Hamilton, accused of murdering Kingi, who died following the incident in Rānui Street, Hamilton, about 11.30pm on Friday, July 28 last year.

The Crown case against the pair alleges they were the elder two of three girls - at the time aged 15, 13 and 12 - who were caught in the act of breaking into a Nissan Primera owned by Kingi and his partner, Vicki-Lee Reihana, which was parked outside their house.

The couple caught the youngest girl, while the other two ran off - only to return soon after armed with a knife and a screwdriver.

There was a confrontation and it's alleged the oldest girl, who had the knife, stabbed Kingi in the heart, fatally injuring him.

On the trial's eighth day on Wednesday the jury heard the closings of Crown prosecutor Philip Morgan QC; followed by Ron Mansfield, the counsel for the older girl; and Roger Laybourn, who is acting for the younger girl.

There was no dispute about what happened, Morgan told the jurors. The real issue was intent.

The two girls had made "a conscious decision" to go back to the car and rescue their younger friend, he said.

"What gave them the mental fortitude? What made them so staunch?"

The pair had been shouting "Let her go or we'll do you" - or as the defence version put it: "Let her go and we'll go", which was still a threat, Morgan said.

Kingi had been shouting back: "Come on then, I will take you on".

"We have, have we not, the irresistible force and the immovable object," Morgan said.

"It was not a hard blow. It was one smooth, thrusting, deliberate action that penetrates this man's chest up to the hilt.

"When [the older girl] made that stabbing action she intended to cause the death of the deceased. Alternatively, if she intended to cause him serious harm and did so recklessly, then she is guilty of murder."

There was no chance the older girl was acting in self defence, Morgan said.

"She was angry because [the couple] would not do as they were told."

The intention was to "inflict violence on these two for the purpose of achieving their object: Freeing [the youngest girl]".

More soon.

-Stuff/Mike Mather.