Victorian man Ian Thomas found guilty of murdering his parents in 2013

Ian Thomas strangled his mother, shot and violently bludgeoned his father and then lied about it.

After a 21-day trial, a jury found him guilty of two counts of murder over the deaths of Pauline, 63, and William Thomas, 65, at the family's Wangaratta property in Victoria on April 21, 2013.

They rejected Thomas' defence that he came home to find his mother dead in a shed at the back of the property, then shot his father in self-defence.

Thomas strangled his mother with cable ties then armed himself with a pick-axe handle and a shot gun and lay in wait for William to return, the Victorian Supreme Court jury found.

Thomas, 38, shot his father, fatally, in the chest with a single-barrel shotgun then used a pick-axe handle to bash his brains in.

Crown prosecutor Peter Rose said William Thomas was eviscerated by his son who wanted to exorcise his hatred.

"He takes to him with the pick axe handle, and that is among the most violent attacks that one can get."

Thomas said in his defence he had wrestled the shotgun out of his father's hands after his father pointed the firearm at him and cocked it.

Once he had the gun, Thomas pulled the trigger deliberately, he told the court, but he said he did it in self-defence.

There was nothing in the house that indicated there was any struggle between Thomas and his father, nor any injuries on Thomas.

"There's no threat to Ian, and Ian shoots his father in cold blood," Mr Rose said.

William Thomas had had a hip replacement in 2012 and had recently endured a bout of pneumonia at the time of his death.

Neighbours and friends described William and Pauline Thomas as a harmonious couple.

Thomas did not react after the jury delivered the verdict of guilty on two counts of murder.

He was remanded into custody and will return to court for a plea hearing on a date to be set.