Since Lyle and Marie McCann were not killed simultaneously, prosecutors arguing in court this week say that makes the second death "as close to near murder as you can get, without being murder."

That scenario forms a central part of the Crown's argument that Travis Vader deserves a harsher sentence for the second killing. 

• ■TIMELINE: Vader and the McCanns: 6 years to a decision

On Monday, the first day of Vader's week-long sentencing hearing, Justice Denny Thomas said the Crown would seek two life sentences to be served at the same time.

But in a 27-page brief filed with the court, prosecutors instead argue the second killing should result in a longer sentence than the first.

'We do not know which killing took place first'

Vader was convicted in October on two counts of manslaughter in the deaths of the St. Albert couple, whose bodies have never been found.

In its brief, the prosecution admits it doesn't know which victim was killed first.

"You don't need to be a doctor to know that inflicting bodily harm on an 80-year-old can result in life-threatening injuries," Crown prosecutor Ashley Finlayson argues in the brief. "After Vader killed the first McCann, he must have known the likelihood of harming the second person would have the same effect."

The Crown proposes a sentence in the range of 12 to 15 years for the first killing, and a life sentence for the second. Both sentences would be served at the same time.

• ■'Thrown to the wolves': Travis Vader testifies about violence and humiliation in custody
• ■Defence argues Travis Vader should serve no more jail time after claims of pre-trial abuse

'The deaths could have resulted from punches'

But the defence insists the Crown's theories are "premised upon conjecture and speculation." 

"There has never been any evidence that Mr. Vader intended to cause serious bodily injury or life-threatening injury to the McCanns," Nate Whitling argues in his own court brief.

While Whitling acknowledged evidence of gunshot residue was found, he said there is no proof beyond a reasonable doubt that the McCanns were shot.

The defence has its own theory about how the two seniors could have died.

"The deaths in the present case could have been caused by the McCanns encountering Mr. Vader when he was attempting to steal their property," according to the defence brief. "Both resisted, the fight escalated, and in the struggle both McCanns were fatally injured.

"The deaths could have resulted from punches, or other acts which were not likely to result in serious injury or life-threatening injuries."

The defence says that puts Vader at the lowest end of the scale in terms of blameworthiness. Whitling is seeking a sentence of four to six years that could be shortened after Vader is given credit for time already served in custody, or for any possible violations of his constitutional rights. If the defence argument wins the day, the convicted killer could walk away a free man, either immediately or within the next year or two.

Whitling also argues the judge found Vader's crime was motivated by drug addictions, and that he had a limited criminal record at the time of the killings.

'Cool, calm and collected'

In passing sentence, a judge is entitled to take into consideration what's referred to as "post-offence conduct." That can include evidence of a lack of remorse.

Prosecutors argue that Vader should face a harsher sentence because of the way he acted after he killed the McCanns. They describe him as "cool, calm and collected" after a confrontation "that would be shocking to almost anyone else."

Trial evidence showed that after he killed the McCanns and disposed of their bodies, Vader used the elderly couple's cellphone to repeatedly send love messages to his then-girlfriend, Amber Williams, and spent the elderly couple's money to buy beer and a phone card.  

"It demonstrates his lack of remorse for whatever horrible event had just occurred," the Crown argues. "He wasn't agonizing over that, but was consumed by his self-interest in Amber Williams. His concerns were about self-gratification and self-preservation."

Vader continues to maintain his innocence. Though he has been convicted, his lawyers say the 44-year-old has the right to remain silent.

"The accused is entitled to defend himself on the basis that the victims are not dead, and also on the basis that if they were killed, they were killed by someone else," the defence argues.

'Mr. Vader's dangerousness'

On the first day of the sentencing hearing, Justice Thomas gave a clear signal that he also wants to consider two other factors before he passes sentence: delayed parole and what he called, "Mr. Vader's dangerousness."

A section of the Criminal Code allows a judge to force an offender to serve half his sentence, or 10 years, whichever is less, before becoming eligible for parole. That section can be applied if an offender is given a sentence as low as two years, or as long as life.

On the subject of how dangerous Vader might be, the judge pointed out that he heard evidence during the trial that Vader made "threats of harm" against a Crown witness, who was forced to go into witness protection.

"That may play into the dangerousness of Mr. Vader and how long the length of sentence should be," Thomas said.

Vader has spent much of the last six and a half years behind bars, but not all of it in relation to the McCann deaths.

In its sentencing brief, the Crown went through an exhaustive review of the other charges Vader faced and his time spent in custody.

Prosecutors argue he should be granted about three years credit for time served. Typically one day spent in pre-sentence custody is multiplied by one-and-a-half or two, so it's possible Vader could get up to six years knocked off his final sentence.