An inmate has died at the federal psychiatric prison in Saskatoon.

Denis Grandbois, an inmate at the Regional Psychiatric Center, died Thursday of “apparent natural causes,” according to a press release from the Correctional Service of Canada.

The Federal Prison Service indicates that Grandbois’ next of kin have been informed.

Grandbois was charged with second-degree murder in the fatal shooting of his wife, Beverly, in July 1997. He pleaded not guilty on grounds of mental disorder, but was convicted of murder after a jury trial , according to court records.

Grandbois attempted to have the murder conviction overturned in a 2003 appeal, arguing that the verdict was unreasonable because it contradicted the opinions of three psychiatrists who had testified for the defense.

There was no doubt that Grandbois suffered from a mental illness, according to Justice James MacPherson wrote in his 2003 decision. He had been hospitalized several times and during the trial, three psychiatric experts unanimously diagnosed him with bipolar affective disorder with delusions, characterized by mood swings ranging from depression to hypomania.

But there were signs that Grandbois could have manufactured the defense.

“There was also evidence that in the weeks before the shooting he was applying for disability benefits and that he may have exaggerated his symptoms,” MacPherson said.

“He told his sister-in-law that he expected to receive disability benefits because he knew how to fool psychologists. On the day of the offense he went to a friend’s house to collect ammunition and sent his daughters for a walk,” he said.

“Although he later told defense psychiatrists that he was guided by a voice in his head at the time of the shooting, he did not mention that voice during his first conversation with police.”

Although Grandbois argued that he was incapable of understanding the moral gravity of the murder when he shot his wife, the jury ultimately disbelieved him.

The Crown presented no psychiatric evidence and Grandbois was convicted of second-degree murder.

Grandbois died Thursday at the Regional Psychiatric Center in Saskatoon. He had been serving an indeterminate sentence since October 1998. He was 65 years old.