QUEBEC CITY - A retired Quebec Superior court judge is on trial for first-degree murder, accused of shooting his disabled wife and making it look like a suicide.

Jacques Delisle, 77, has pleaded not guilty.

In court on Tuesday, the Crown prosecution laid out its theory concerning the 2009 death: that Delisle had shot his wife so he could move in with his mistress.

Initially deemed a suicide

Delisle's wife, 71-year-old Marie-Nicole Rainville, was found dead in November 2009 in what appeared to be a suicide.

Rainville was partially paralyzed due to a stroke, and had a broken ankle. She used a wheelchair.

Delisle, discovered the body, and called 9-1-1 to say he and his wife had had an argument that morning, and that after running errands he had returned home to find his wife's body in a chair, with a gunshot wound to the temple.

Police considered it a suicide until forensic investigators discovered black gunshot residue on the palm of Rainville's hand. Usually when someone fires a weapon such residue is found on the fingers and back of the hand.

A municipal police investigator also testified that there was an "abnormal and inexplicable" black smoke stain in the palm of the woman's hand -- a strange location for such gunshot residue.

The investigator also deemed the choice of suicide method suspicious; in all his years on the police force he said he had never seen a woman kill herself with a revolver.

The jury trial heard a 911 call from Delisle, during which he explained that he had returned home to find his wife's body.

In the call the ex-judge, exhaling heavily, explained that his wife had been completely paralyzed on her right side following a stroke.

"My wife killed herself," Delisle told the 911 operator.

"There's a revolver next to her."

Alleged affair with secretary

Suspicion led police to look closely at Delisle's life.

They found evidence that the judge, who had retired earlier that year to care for his wife, had a mistress: his former secretary.

According to the prosecution, she had been having an affair with the judge -- and they had apparently discussed the possibility of living together.

Respected judge

Delisle is one of the most experienced justices in Quebec.

He spent the better part of his career on the bench as a Superior Court judge, and was also a justice on the Court of Appeal.

He is probably more experienced that anyone else in the courtroom, although his defence is being led by noted lawyer Jacques Larochelle, the same man who defended Basil Parasiris.