The convicted killer of a popular young Vancouver artist is appealing his conviction, saying he should have been found guilty of a lesser charge.

Dennis Robert White fatally shot 23-year-old Lee Matasi, execution style, outside a downtown nightclub in December 2005.

White received an automatic life sentence in February 2008 when he was convicted of second-degree murder, and given 16 years in prison.

But his lawyers argue the shooting was an accident, and should have been prosecuted with the less serious sentence for manslaughter.

"I think [the sentence] is at the high end and I think that some of the character of the individual wasn't taken into consideration," defence lawyer Terry LaLiberte said.

But Crown prosecutors want the B.C. Court of Appeal to uphold the original conviction, saying White chased the young man and beat him with the gun before shooting him in the chest, proving his intentions.

Matasi and White had a confrontation after White fired a gun outside the Red Room nightclub, and Matasi objected. White hit Matasi in the head with the gun and then shot him in the chest.

Footage from a nightclub security camera captured the victim trying to escape his killer before he was shot. Footage from another camera showed Matasi's friends tending to him after the shooting.

Matasi was an avid skateboarder, and a Vancouver skateboard park was named in his honour. He also had a promising career as an artist and was weeks away from moving to Paris where he was going to live for a year with his girlfriend.

During the 2008 trial, the defense admitted Matasi had been shot by White but contended the Crown had failed to prove there was intention to kill.

Matasi's mother, Susan Jessop, disagrees.

"No one leaves home with a gun with good intentions ... in an urban environment," she said.

"What a waste. What a bloody waste this whole thing has been about," she said. "One young man is dead, that's my son, another man's going to jail for a very long time, and for what?"

A ruling in the appeal is not expected for at least three months.