A Calgary judge has found Allan Shyback guilty of manslaughter in the 2012 death of his common-law wife Lisa Mitchell.

Mitchell, 31, was last seen alive at her Ogden home in 2012 and the Crown said that Shyback killed her and hid her body in the basement for two years until it was discovered by police.

Shyback was accused of second-degree murder and causing an indignity to a body in the incident.

On Thursday morning, Justice Rosemary Nation found him guilty of the lesser charge of manslaughter.

Nation also found him guilty of causing an indiginity to a human body.

During his trial, Shyback said that he was a victim of domestic abuse and strangled Mitchell in self-defence.

However, Nation, in her reasons, rejected that claim because she found that once Shyback had Mitchell pinned to the floor, he overpowered her and continued to use excessive force until she was dead.

She did find doubt about intent behind the killing, ruling out the second-degree murder charge in the case.

Mitchell's mother and borther attended the hearing and said they are glad to hear about the conviction.

"It's unbelievable what he did and what he did, especially, afterwards," said Peggy Mitchell. "That's what hurts the most; how he could treat someone like that, that's the worst thing anyone could do."

"We were always hoping he would get the worst for what he did," said Ryan Mitchell. "At the same time, the medical evidence was what it was and we accept that."

Crown prosecutor Jayme Williams said that Justice Nation did fulfill their desire to have Shyback convicted in the unlawful death of Lisa Mitchell.

"In that sense, the court has done what we asked them to do," she said.

Balfour Der, Shyback's defence lawyer, said Shyback is remorseful about the incident and the worst thing is the optics of the whole thing.

"What happened to the body afterwards, being cemented into basement floor and a lot of people look at that and say 'that's gotta be murder' and my client's quite relieved and recognizes the optics and what occurred afterwards was serious. A conviction for murder was definitely on the table and we were quite convinced on evidence it was not murder."

Shyback was arrested in 2014 after he admitted to undercover officers that he’d killed Mitchell and put her body into a plastic bin and encased it in concrete in the basement.

Sentencing in the case is scheduled for September 20.