After Adrian Phillips shot Bayden Williams three times including in the head, fatally wounding the young father, he pulled the body off an isolated road and down a bank.

"It didn't seem right to leave him there," Phillips told the High Court at Hamilton through tears.

Then he threw away shotgun casings and feeling "unsafe", he fled the Kopu-Hikuai Rd scene on August 5, 2020.

Phillips is giving testimony in his trial for the murder of Williams, 20, of Tairua.

The 24-year-old Ngatea man had smoked weed earlier in the day and while sitting on a beach near Miranda he received a message telling him Williams was on his way to dinner in Thames.

He wanted to confront Williams on his own because he believed Williams owed him an apology over a fight they were involved in earlier that year.

The Crown case is that Phillips harboured a grudge against Williams since the altercation in January 2020.

Phillips said Williams humiliated him when he held him down as Peter Randall, the father of Phillips' girlfriend Macy Randall and Williams' ex-girlfriend Chloe Randall, was strangled almost to the point of unconsciousness by Williams' father Lance Williams.

When he realised Williams was on his way to Chloe's house in Thames to rekindle their relationship he decided to intercept Williams to elicit the apology while Lance Williams was not there.

He passed Williams on the Kopu-Hikuai Rd and did a u-turn, flashing his lights at Williams in his Jaguar and began tailgating him.

Bayden Williams, 20, was a popular member of the Tairua community when he was fatally shot on the Kopu-Hikuai Rd in August 2020. Photo / NZME

The pair drove erratically on both sides of the road before Williams braked near a corner, causing Phillips' ute to hit the rear of Williams' car, pushing it into a backward slide down a bank.

Both got out of their cars with Phillips grabbing his unloaded sawn-off shotgun for protection - he believed Williams always carried a knife.

"At the very worst, I'd be able to keep him away from me."

With the Jaguar lights blinding Phillips, he could only see Williams' silhouette.

"I just froze. I was very frightened. I thought he was going to stab and kill me."

According to Phillips, Williams charged up the bank yelling: "I'll f**ken cut you up. I'll f**ken kill you".

Phillips loaded the gun and fired a warning shot into the ground but maintains Williams continued to rush toward him.

He retreated, reloaded and fired again hitting Williams in the thigh but said Williams continued to charge upwards at him.

Phillips repeated the action and fired again, striking Williams in the shoulder, but still Williams continued to come at him, he said.

"He kept rushing toward me. It didn't seem to affect him at all."

As Williams got to the roadside Phillips fired again, shooting Williams in the head.

"I fired the last shot and he fell to the ground."

Phillips, who had to compose himself during the testimony, said immediately after he dragged Williams' body back towards his Jaguar by his jersey because he "didn't want to look".

He picked up shell casings and threw them down the bank.

Phillips said "it didn't feel real" and he didn't feel safe so he drove toward home.

On the way the apprentice mechanic stopped to fix his damaged car and threw away the gun and the rest of the ammunition.

He called Macy and she drove to meet him before he explained what he had done.

He told her: "I think I might have hurt Bayden".

"I felt sick to my stomach. I blame myself for what happened."

She called the police and after showering and changing his clothes Phillips heard from outside the home he shared with his mother and Macy: "Adrian, it's the police. Come out with your hands up."

Earlier in his testimony Phillips described the severe psychological impact serious burns had on him after he accidentally set himself alight while pouring accelerant on a bonfire in December 2018.

He spent three weeks in Waikato Hospital and need four surgeries for skin grafts to his left hand.

That left him considering suicide on a daily basis and seeking counselling. It culminated in him leaving his job and smoking cannabis most days to relieve his anxiety.

Defence counsel Ron Mansfield asked Phillips if he intended to hurt or kill Williams that night and Phillips denied he did.

He only wanted to end the feud between himself and Williams, who had once been a mate, to help him recover from his mental struggles, particularly as it appeared Williams was coming back into their lives.

The defence case is that Phillips was acting in self-defence.

Phillips continues to give evidence this afternoon.

- Natalie Akoorie, Open Justice