Bret McCann is haunted by a nightmare.  

"[Travis] Vader kills one of my parents and the other one watches, knowing that they are next," McCann said Monday outside the Edmonton courthouse. "I can't get that vision out of my head. And I know I'll have that nightmare until … forever."

McCann spoke to reporters Monday on the first day of a sentencing hearing for the man who killed his parents.

Vader was convicted in October on two counts of manslaughter. He is expected to take the stand on Tuesday.

The sentencing hearing in Edmonton Court of Queen's Bench could last all week. The defence is expected to ask Justice Denny Thomas to impose a sentence of four to six years. Crown prosecutors will argue that Vader should serve two concurrent life sentences for killing Lyle and Marie McCann. 

The St. Albert, Alta., couple was last seen more than six years ago. Their bodies have not been found.

• ■Sentencing hearing begins for Travis Vader, convicted in deaths of St. Albert couple.

Outside the courthouse on Monday, Bret McCann called the possibility of a shorter sentence "absurd."

"He's killed two people in a robbery with a firearm," McCann said of Vader. "Covered it up. Lied about it for years. I think a four-to-six-year sentence ... with time off he'll be out on the street carrying on in a year. Less than a year."  

Vader sat expressionless in the prisoner's box on the first day of the hearing, sporting a bandaged right hand and splinted fingers. Defence lawyer Nate Whitling refused to comment on the reason for his client's injury.

The defence is expected to argue that Vader's constitutional rights were violated while he was in custody. Vader is expected to tell the court about jail conditions and argue for a reduced sentence or even a stay of the proceedings.

Eight victim impact statements were read Monday in the courtroom.

'Our loss is huge,' son of couple says

The first statement was filed by the couple's granddaughter, Nicole Walshe, who lives in Australia. Her statement was read into the record by the prosecution.

"My innocence has been shattered," Walshe wrote. "I live every day with a deep sadness."

The young mother of two said her grandparents' deaths have taught her that there are "truly evil people" in the world.

"I never thought someone could be so cruel to hurt an elderly person, let alone killing them," her statement said.

In his victim impact statement, Walshe's husband, Casey, wrote that he dreads the day he will have to explain to his two daughters what happened to their great-grandparents.

"I will have to expose them to the horror and selfish cruelty that exists in the world so close to us," he wrote.  

When his turn came, Bret McCann set up photos of his grandchildren for the judge to see.

The first picture showed the smiling elderly couple holding their first great-grandchild. The second photo showed Walshe's two little girls, born after the McCanns were killed.

"Our loss is huge," he said. "Our pain everlasting. I will never forget or forgive what Travis Vader has done."

Later outside court, McCann said only one thing could make him forgive Vader.

"If he were to stand up and say what happened to my parents, then I could say that I could forgive him."  

The complex and sensational case has dragged on for more than six years.

The McCanns were last seen alive in July 2010 at a gas station in their hometown of St. Albert. It was the first day of a road trip to British Columbia. Their burned out RV was found days later in a rural area near Edson, Alta.

Vader was originally found guilty in September of two counts of second-degree murder.

But in that decision, Thomas relied on an outdated section of the Criminal Code, prompting Vader's legal team to apply for a mistrial. As a result, the conviction was downgraded to manslaughter.