Kim Walker is seen as he attended his 2007 trial in Yorkton, Sask. (Karl Kopan/Yorkton News Review/Canadian Press)

The Saskatchewan man convicted of killing his daughter's boyfriend is back before the courts, arguing he was in an altered state of mind when the fatal shooting took place.

Kim Walker, 52, is serving a life sentence for the shooting death of James Hayward in Yorkton, Sask., in 2003.

Hayward, 24, was dating Walker's daughter Jadah, who was 16 at the time and addicted to morphine.

At his trial, Walker maintained Hayward was responsible for the girl's addiction. Walker went to Hayward's house and shot him five times, including once in the back.

On Wednesday Walker was in the Court of Appeal for Saskatchewan in Regina, where his lawyer argued there was fresh evidence that should be considered in the case.

The defence has found a psychiatrist who said that Walker was in a "dissociative" state at the time of the killing.

The defence wants the Court of Appeal to consider that new evidence.

Normally an appeal court will only review a case based on the evidence that was entered at trial.

The hearing on Wednesday dealt with the issue of whether or not the psychiatrist's opinion could form part of the appeal.

The court did not decide the issue right away, but said it would determine the admissibility of the psychiatrist's opinion prior to hearing Walker's conviction appeal.

There was no date set for the actual appeal.