An inmate has died in federal psychiatric prison in Saskatoon.

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

The federal prison service says Grandbois’ next of kin have been notified.

Grandbois was charged with second degree murder in the fatal shooting of his wife, Beverly, in July 1997. He entered a plea of not criminally responsible for reason of mental disorder but was convicted on the murder charge after jury trial, according to court records.

Grandbois tried to have the murder conviction overturned in a 2003 appeal, arguing the verdict was unreasonable because it conflicted with the opinions of three psychiatrists who testified for the defence.

There was no doubt that Grandbois was mentally ill, Justice James MacPherson wrote in his 2003 decision. He had been hospitalized many times, and at trial, he was unanimously diagnosed by three psychiatric experts as suffering from bipolar affective disorder with delusions, characterized by mood swings ranging from depression to hypomania.

But there were signs Grandbois may have manufactured the defence.

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

“He told his sister-in-law that he expected to receive disability benefits as he knew how to fool the psychologists. On the day of the offence, he drove to a friends home to collect ammunition and sent his daughters for a walk,” he said.

“While he later told defence psychiatrists that he was being guided by a voice in his head at the time of the shooting, he did not mention the voice in his initial conversation with the police.”

Although Grandbois made the case that he was incapable of grasping the moral gravity of the killing when he shot his wife, ultimately, the jury didn’t buy it.

The Crown called no psychiatric evidence, and Grandbois was convicted of second degree murder.

Grandbois died at Saskatoon’s Regional Psychiatric Centre on Thursday. He had been serving an indeterminate sentence since October 1998. He was 65-years-old.