The lawyer for a man who admitted to killing his wife and hiding her body for years says he acted in self-defence but the prosecution argues Allan Shyback tailored his story to make himself look like the victim.

A judge will now decide if Shyback is guilty of the second degree murder of Lisa Mitchell.

Shyback confessed to strangling Mitchell, his common-law wife, to death in 2012 but told an undercover officer she attacked him first.

"She kind of came towards me with the knife and I don't know if she - at the time -I thought she was trying to stab me things happened, I wound up trying to hold her back, my hands were around her neck  I remember trying to let go and not being able to,” says Shyback.

In closing arguments, Shyback’s lawyer Balfour Der said If his client is found guilty of anything it should be manslaughter, not murder because Shyback didn’t intend to kill Mitchell.

“He didn't try to cause her harm, he was defending himself, he loved this woman,” Der told the court.

Shyback testified he as a victim of domestic abuse but prosecutor Jayme Williams told the judge “Shyback’s version appear tailored to avoid a murder charge.”

Both sides agree Shyback is guilty of causing an indignity to a body. 

Mitchell’s corpse was found cemented in a container in the couple’s basement for more than two years after she vanished.

Her two children were living upstairs oblivious to their mother’s decomposing remains.

Shyback admitted he took steps to cover his tracks.

“I wound up hiding the body and placing some text messages and emails that are from her to family and stuff saying that she'd left,” says Shyback.

The trial is by judge alone so a jury is not deciding Shyback’s fate.

Justice Rosemary Nation can acquit Shyback, find him guilty of murder or find him guilty of manslaughter.

The verdict will be handed down May 18th.

(With files from Jordan Kanygin)