"He thinks his best mate is messing around with the girl he fancies. It's the oldest story in the book: jealousy."
He told the jury that McDonald was still guilty of murder, even if they accepted McDonald's claim that Mr Kahi broke into his house and threatened him.
"Is it reasonable to shoot an unarmed man, even if he thought he might be armed, in the back while he was ducking for cover?
"It can't be self-defence to shoot somebody in the back like that. He acted with murderous intent. He meant to do it. He meant to kill him with those shots."
He said McDonald knew the gun was capable of killing someone because a friend, whose name is suppressed, had shot a man with the same type of rifle in 2008 and had stood trial only three weeks before Mr Kahi was shot dead.
"He would have to have known that when you shoot somebody seven times with this gun, death might result."
Mr Dixon said McDonald's claim that he had shot the gun in a random arc was also clearly not true given only two shots had missed Mr Kahi.
"Seven of nine shots hit Keith and this man says he was shooting just anywhere? It doesn't make sense."
Mr Dixon said McDonald's evidence was riddled with inconsistencies.
For example, McDonald said Mr Kahi had pushed him over a couch before he picked up the gun, yet police photographs show a glass sitting upright where he said he fell.
"He's been thrown over this couch, grabbed the gun and gone rata-tat-tat - by his account - without knocking over the glass? That just doesn't make sense in my submission."
Mr Kahi had moved out of the house earlier that day and the Crown says he broke in to retrieve some of his things because he was locked out. He did not know that McDonald was home.
Defence counsel Mark Edgar argued his client had been "consumed by fear" when he woke to find a man in his dark bedroom.
"This is a man who's already got anxiety and trust issues and he's just smoked meth - and this is real."
He said his client's first instinct was to protect himself after an argument between the pair broke out.
"You need to consider what Mr Kahi's presence in the house may have constituted in Mr McDonald's mind. We know that Mr Kahi was capable of unpredictable and violent behaviour, and we know that he carries grudges.
"McDonald was unsure why Mr Kahi was there and he was distrustful as to his motives. There was a threat to kill, a push over the couch and he shoots," Mr Edgar said.
"This was not a focused assassination, it's more consistent with a frightened, panicked, freaked-out response.
"When Mr Kahi entered that house by stealth in circumstances where Mr McDonald thought he had gone... that's the one issue that led to a chain of events that led to the death of a man," Mr Edgar said.
"Fear is right at the heart of this trial."
Justice Rebecca Ellis will give her closing address tomorrow before the jury retires to consider its verdict.
