Jurors heard Harnwell was found about eight days later, hiding again, this time in a ceiling cavity at a relative's house in Onehunga.
Tamatoa and Harnwell hated each other, Teppett told jurors.
"Things were going seriously downhill between them."
The court heard Tamatoa celebrated his birthday at Trig Rd last July, and Harnwell was there, giving him money and methamphetamine as presents.
But Harnwell was shot at when leaving the property on Auckland's northwestern outskirts the next day, and he blamed Tamatoa, the prosecutor said.
Tamatoa was paranoid about his ex-partner's relationships with other men, and was enraged to see Harnwell's possessions in the woman's bedroom one day.
Teppett said Tamatoa helped himself to thousands of dollars worth of ephedrine, a meth precursor.
Tamatoa's ex-girlfriend texted him on August 4 to say someone was coming to collect payment for stolen drugs.
According to Teppett, Tamatoa said he would come to protect her.
But the pair argued before Tamatoa held a handgun to her throat and said he would kill her.
"She, remarkably perhaps, carried on arguing with him," Teppett said.
Other people came and left that night, some of them smoking meth inside together.
Tamatoa went outside, started doing donuts with his car in a paddock, then took off and returned 10-15 minutes later.
Teppett said Tamatoa then started smashing things in a bedroom before crying and saying he missed his ex and wanted to get back together.
"It's the last time Mr Tamatoa was seen without stab injuries," Teppett said.
That's because Tamatoa went to a bedroom where Harnwell was.
KNIFE HANDLE BROKEN
"What appears not to be in dispute is that while inside that bedroom, Mr Harnwell stabbed Mr Tamatoa," Teppett added. "The handle of the knife broke."
Tamatoa then stumbled into the woman's bedroom and collapsed, and she reportedly heard someone say: "He'll never hurt you again, girl".
Another man at the property called 111 but Harnwell fled on foot.
Tamatoa's Ford Explorer blocked ambulances and police from accessing a long driveway, and Tamatoa was dead by 2.56am on Wednesday, August 5 last year.
Harnwell then lay low, got rid of some clothes and deleted his Facebook account.
After police caught him, he claimed Tamatoa fell on the knife.
The Crown said Harnwell had been itching for a fight with Tamatoa over the stolen drugs and the shooting.
"Mr Harnwell just happened to get to Mr Tamatoa first," Teppett said.
"If this had been an accident, why flee, rather than help?"
Defence counsel Andrew Speed said Harnwell was acting in self-defence, or in defence of Tamatoa's ex-girlfriend.
Speed said Harnwell did not intentionally kill Tamatoa, and did not know the injury inflicted would likely cause death.
"If you do find he acted in self-defence or the defence of another, then the accused will not have acted recklessly."
Jurors expected to hear from more than 30 witnesses, including police, forensic scientists and West Auckland residents.
Today, constables who attended the Trig Rd scene said intelligence received on the way to the house indicated police might want to arm themselves.
Officers were at a safe forward point by 2.15am but Tamatoa's car about 10-20m from the road slowed their approach.
"I heard a female yelling and screaming 'he's bleeding, you have to get down there'," Constable Victoria Mason told the court.
The trial before Justice Mathew Downs and the jury continues.
