He said the cut on Donner's neck would have caused his death within three to five minutes.
Balachandra, appearing via audio visual link from Canada, is one of 17 witnesses expected to be called by Crown prosecutors Steve Manning and Cam Stuart."The carotid artery was completely severed, it's one of the four arteries that take blood to the brain from the heart," Balachandra said.
Balachandra examined Donner's body in Palmerston North Hospital on March 6, two days after Donner died.
The doctor referred to images of injuries contained in a booklet provided to the jury.
Donner had two cuts on his neck, one 10.5cm deep, the other 5cm deep. Balachandra believed both injuries were caused by the same weapon, a knife.
Donner also had 14 cuts and abrasions.
On Monday, the court had heard Hanara and four other teenagers entered the Flaxmere Tavern carpark in a bid to steal alcohol on March 4.
Donner, who was known by some Flaxmere locals as a homeless person, was in the carpark looking for cigarette butts and loaned Hanara his torch.
When the teenager refused to return it, Donner became angry. An attack escalated, and a beer bottle was smashed in Donner's face.
He escaped the yard and ran out behind the tavern where the attack continued.
The Crown alleges that Hanara disappeared behind a block wall, then reappeared with a knife in his hand.
Donner retreated and Hanara followed him, then stabbed him four times, the Crown says.
