"RIP Boardman ... see you in hell," Hohepa Paetai Bean signed off in August 2018.

In October Darren Boardman,40, died from a rifle wound to his right upper back, shot by Bean who is pleading not guilty to his murder.

The 43-year-old pleaded guilty to manslaughter saying his life was in danger but the Crown has rejected this.

Bean had been dating Toni Carter for 20 years when she left him for Mr Boardman. The two men's longstanding friendship quickly turned sour and abusive text messages between them ensued.

The jury deciding Bean's fate spent hours in Coffs Harbour Supreme Court on Wednesday poring over the text exchanges that led up to the fatal shooting on a Dundurrabin property on October 18, 2018.

"Any time any place, f***ing here right now, you f***ing parasite all f***ing talk aye. You weak as piss dog c***," Bean wrote to Mr Boardman, in one of many "challenges" the Crown says he followed through on.

But Bean's defence lawyer Jason Watts said there was equal malice and threats from the deceased, who at one stage ran over Bean's letterbox.

"Tough guy alright running over my mailbox what a f***ing amateur," Bean wrote in response.

Mr Watts said Mr Boardman often sent his client menacing messages that he was being watched.

"Maggot scared c*** got bright lights at your place, bit worried someone might sneak up on you," he wrote to Bean in September.

Ms Carter and Mr Boardman had recently relocated to Queensland but returned to Coffs Harbour for a medical appointment when she paid a visit to her ex.

That afternoon Mr Boardman drove to pick Ms Carter up and ran into Bean's ute. He returned with a rifle and shot Mr Boardman while still seated inside.

Senior Constable Peter Ziesig and other officers were later called to a nearby highway where Mr Boardman's body was lying facedown in the back of another truck.

Sen Const Ziesig said they ushered a highly distressed Ms Carter out of the rain and into a police vehicle where she relayed what happened.

"He turned up flying down my driveway and smashed into the back of the car... no idea why he was going so fast," the officer recalled her saying.

Bean's defence says he was standing in the way of Mr Boardman's speeding car before jumping away and fetching his rifle for safety.

By the time Sergeant John McCarthy turned up at the property, footage from his body-worn camera showed both cars wedged together but Bean had fled.

Bean later sent a text to Ms Carter with words to the effect: "We're going to have to say he was playing with the gun and it went off".

The trial continues.

Australian Associated Press