A relative of homicide victim Clifford Umuhuri was temporarily barred from the courtroom today after he stood up and yelled as a witness emotionally recounted the final moments of Umuhuri's life.

"F***ing pussy!" the man shouted from the gallery as he interrupted Gary Campbell, one of three people who were with Umuhuri during the pre-dawn methamphetamine deal that turned fatal on June 1, 2020.

Campbell was telling jurors in the High Court at Auckland, where Michael Filoa and Aaron Davis are on trial for robbery and murder, that he didn't know how to give CPR but tried anyway out of desperation after watching a bystander who was tiring as he tried in vain to revive Umuhuri.

"I had a go at doing it," he said just before the interruption rang out. "That's when I saw Cliff's eyes go in the back of his head and he just stopped breathing."

A truck driver who had fallen on hard times amid the nation's first Covid-19 lockdown, resulting in losing a job he'd held for 15 years and living out of his car, Campbell had spent the days before the shooting smoking meth with longtime friend Beatrice Gage, her brother Hadyn Gage and Umuhuri. He had heard of Umuhuri previously, knowing he was a Mongrel Mob gang member from Bay of Plenty, but he had never met the man previously, he said.

Filoa and Davis are accused of having plotted to rob Umuhuri as he attempted to purchase thousands of dollars worth of meth from them at a time when the drug was harder to come by due to the lockdown.

Michael Filoa (left) and Aaron Davis are on trial for murder in the High Court at Auckland. Photo / Dean Purcell

The duo likely didn't expect Umuhuri to fight back as he was being ripped off, prosecutors suggested last week during their opening statement. Lawyers for the two have acknowledged both were present that morning and Filoa is the person who pulled the trigger, but they said there was never a plan to rob Umuhuri and suggested the shooting was in self-defence.

On the witness stand today, Campbell recalled driving his friends to a Mobil petrol station in Panmure on the morning of the shooting, knowing Beatrice Gage and Umuhuri intended to conduct another meth deal but not wanting to know many details. They were there for about 15 minutes as Umuhuri ordered pies and joked with the attendant before Beatrice Gage got a text instructing them to head to a nearby Countdown car park, he recalled.

At the grocery store, he noticed two men inside a white car as it circled his own car. The cars then convoyed to a quiet neighbourhood in Auckland suburb St Johns, where Umuhuri got out of his vehicle and entered the other, he said.

"I was back on my phone again," he said. "I sort of started to doze off, and then Haydn said, 'Don't go to sleep, don't go to sleep, just be aware.'"

About four or five minutes after they arrived, Campbell said he heard a "shuffle" as the other car started rocking back and forth and he jumped out of his own car alongside the Gage siblings.

"I saw a joker leaning over the roof of the other car and I saw he had fired a couple of shots while Cliff was coming back to my car," he said. "As soon as I heard one [gunshot]...I just jumped back into my car."

Clifford Umuhuri was fatally shot in Auckland in June 2020. Photo / Supplied

Prosecutor Brian Dickey asked him to demonstrate how the shooter was standing, but Campbell said he couldn't see clearly enough to recreate it.

"It was raining [and] my glasses were fogged up," he explained. "It sort of just happened in a big rush."

Umuhuri, he said, was limping and appeared to be in pain as he hurried back to Campbell's vehicle amid the shooting.

Once in the car, Campbell had to decide what to do while Umuhuri and Beatrice Gage shouted opposite commands into his ear, he said, explaining that Umuhuri wanted him to leave immediately while Beatrice Gage wanted to stay and look for her brother, who had run off.

"I was so confused, you know," he recalled, explaining that he stopped the car while Beatrice Gage yelled out, "Haydn! Hadyn! Where are you, Hadyn?"

They decided to leave without Hadyn Gage after a couple minutes and start driving towards Auckland Hospital, but the yelling in the car continued, he said, explaining that he dropped off Beatrice Gage in Greenlane after she told him to let her out.

"She was calling me a useless c***, just yelling at me," he testified. "I know that she didn't mean to. We were all in shock at the time."

Michael Filoa, pictured, is on trial for murder alongside Aaron Davis in the High Court at Auckland. Photo / Dean Purcell

With just him and Umuhuri left in the car, he said he was determined to take his bleeding friend to the hospital but now had Umuhuri yelling in his ear to stop the car.

"It was just all the way coming from the motorway, he was [saying], 'Stop the car! Stop the car! Stop the f***ing car!'" Campbell said, telling jurors that he responded, "No bro, I'm taking you to the hospital."

But he knew Umuhuri was "really, really angry" and so eventually relented, pulling over and calling an ambulance as he stood on the side of the road, he said. That's where police later found him dead.

Beatrice Gage also returned to the witness stand today, remaining combative and often shouting back answers as she reluctantly answered questions from defence lawyer Marie Dyhrberg, who represents Davis.

Dyhrberg noted that in the witness' interview with police just a few days after the shooting, Beatrice Gage described Davis as looking "shocked" and "like he wanted to run" as the shots rang out.

"You were the ones who planned to steal the drugs. You wanted more," Dyhrberg suggested as her voice was drowned out by the witness yelling, "F*** off."

"Cliff had no need to rip them off. He had money," Beatrice Gage said. "You're full of s***."