Kai Yuen has been charged with the murder of Brendan Scott Welsh.

Kai Yuen has been charged with the murder of Brendan Scott Welsh. Photo: Supplied

''I'm f-----, I'm going to jail for the rest of my life for this.''

A confessed killer uttered a similar phrase to friends after gunning down Brendan Scott Welsh behind the Hughes shops in 2010, the ACT Supreme Court heard on Tuesday.

Kai Yuen, 28, has pleaded guilty to Mr Welsh's murder, but claims he did not intend to kill the victim.

The Crown does not accept Yuen's account of the murder.

Mr Welsh was killed by a shotgun blast to the chest at close range while sitting in the driver's seat of a car in Whittle Street, Hughes about 12.30am on May 10, 2010.

The father of four died from his wounds soon after admission to the Canberra Hospital.

Yuen, who had been involved in a feud with Mr Welsh, claims he was pointing the loaded shotgun at the victim when he took his left hand off the barrel to open the car door. He said the gun accidentally discharged, fatally wounding Mr Welsh, when he stumbled on the gutter while holding the weapon in one hand.

The prosecution rejects Yuen's version of events.

The court on Tuesday began a two-day disputed facts hearing to determine what happened on the night.

Two of Yuen's friends, who were with the gunman on the night, gave evidence before Justice Hilary Penfold on Tuesday. The pair, whose accounts differed only slightly, said they had been playing poker with Yuen and another man at a Chisholm home when the defendant received news Mr Welsh had smashed the rear window of his work van.

The witnesses said the four men leapt into a car with the intention of tracking down Mr Welsh.

They said Yuen brought the gun along to scare Mr Welsh and let him know the bad blood between the pair should end.

The group had no luck finding Mr Welsh, checking his northside flat twice to find he was not home.

Instead, they settled on a plan to lure him to Hughes under the pretense of buying drugs and drafted in a fifth man to help.

The court heard neither of the men saw the shooting but were in the getaway car that sped Yuen from the scene and pulled over to dispose of the firearm in a street drain.

The car was pulled over briefly by police and cautioned for speeding but otherwise eluded detection.

Back at the Chisholm home, Yuen told his friends he had shot Mr Welsh and thought he might have killed him. He asked the men to keep the incident secret.

They kept their vow of silence for 2½ months until Yuen told one of the men he was going to hand himself in.

Yuen is expected to enter the witness box when the hearing continues on Wednesday.