Dramatic footage of dairy stabbing shown in court

Arun Kumar was allegedly stabbed to death in his Henderson dairy.

An Auckland dairy owner's wife watched in horror as her husband bled to death on the floor of the shop they had owned for five years.

The knife wound, which severed Arun Kumar's jugular vein and was so deep that it left an imprint on his vertebrae, was allegedly inflicted by a 14-year-old boy during a robbery almost a year ago.

He is on trial in the High Court at Auckland charged with murder, while his 13-year-old co-accused faces a charge of manslaughter after the incident in Henderson's Railside Dairy.

The pair - who have name suppression - also face counts of assault with intent to rob.

Crown prosecutor Kingi Snelgar described the sequence of events before playing CCTV footage of the incident.

Members of the Kumar family wept in the public gallery while the graphic images were played from two different angles.

The younger defendant coloured in a sketch book and his co-accused sat with his head down as the video was shown to the jury.

The pair awoke early on June 10 and Mr Snelgar said it was the younger boy's idea to commit the crime.

"[He] suggested the Railside Dairy was easy to rob, that the two people in the shop were easy targets, targets who wouldn't put up resistance," he said.

He allegedly devised a plan that the older boy, armed with a knife, would demand the money while he stood guard in the doorway with a metal pole.

Mr Snelgar said the 14-year-old went in and out of the shop a couple of times - "scoping out the dairy" - before the incident unfolded.

At 7.24am, the older teen went in and demanded money from Mr Kumar, who called for his wife.

"At this point [the defendant] hit the phone out of her hand and produced a knife, holding it high above his head," Mr Snelgar said.

While Mrs Kumar wrestled the pole from the boy by the door, his co-accused was pictured pursuing Mr Kumar as he retreated behind the counter.

The Crown said he grabbed a small metal pipe to defend himself, but it was not enough.

Mr Snelgar told the court the shopkeeper sustained stab wounds just below his ribs, below the left shoulder and, critically, one to the neck.

Video footage showed the boys flee, briefly pursued by the victim.

But within a couple of steps he reached for his neck and fell to the ground, leaving a bloody handprint on the counter.

Mr Snelgar said the boys ran the short distance home and the murder accused showered and changed his bloodstained clothes.

Police arrived shortly afterwards and arrested the boys.

The prosecutor said the footage would be key evidence as would testimony by a 13-year-old who followed the defendants to the shop that morning.

Mrs Kumar will give evidence tomorrow after the defence open their respective cases.

The trial in the High Court at Auckland before Justice Graham Lang and a jury of six women and six men is scheduled to last about a month.