Travis Vader saw two Alberta seniors as a "target of opportunity" the day he murdered them and stole their money, their SUV and their motorhome, a judge ruled Thursday as he convicted the drug dealer and meth addict on two counts of second-degree murder.

With a television camera recording the event, Court of Queen's Bench Justice Denny Thomas read a summary of his 131-page ruling, in which he accepted much of the evidence presented by the Crown.

"Linking the facts, I have found that Mr. Vader has committed homicide," Thomas told a packed Edmonton courtroom, with Vader's sister and family members of his victims, Lyle and Marie McCann, seated in the front rows.

At one point during the judge's summation, Bobbi Vader gasped audibly when Thomas ruled her brother not guilty of first-degree murder. She then burst into tears and sobbed when Thomas found her brother guilty of the lesser but included charges of second-degree murder.

'Mr. Vader caused the deaths of Lyle and Marie McCann'

Thomas said the evidence proves beyond a reasonable doubt that Vader encountered the McCanns during a five-hour period on July 3, 2010, and that he killed them and stole their property.

"McCanns and their property were a target of opportunity, an opportunity that Vader took. The McCanns were victims of violence. Mr. Vader committed that violence.

"I conclude beyond a reasonable doubt that Mr. Vader caused the deaths of Lyle and Marie McCann."

Justice Denny Thomas finds Travis Vader guilty of murder in the second-degree of Lyle and Marie McCann. 0:39

The judge ruled that the Crown established a timeline for the day that Vader happened upon the McCanns in a campground west of Edmonton. Earlier that day, Vader was broke and driving a stolen Ford truck when he showed up first at a friend's house in the small town of Peers, Alta.

Vader left his friend, and five hours later, returned driving the McCanns' SUV, with cash in his pocket. That day, Vader used the McCanns cellphone several times to text and call his girlfriend.

Thomas said he could not recreate exactly what happened during the robbery but said that doesn't change the underlying facts in the case.

"There was bloodshed, a gun was discharged," he said. "While I cannot reconstruct the exact detail of what occurred, I also have no doubt about the overreaching relevant fact that the McCanns were victims of violence, Mr. Vader inflicted that violence.

"The problem is there are other reasonable possibilities that can take us from a robbery gone bad to that of two dead seniors," Thomas said.

"The most obvious is Mr. Vader encountered the two McCanns together while trying to commit a robbery. The McCanns both physically resisted Mr. Vader, and the confrontation escalated and in the struggle, both the McCanns were fatally injured."

Defence says he plans to appeal

Defence lawyer Brian Beresh said outside the court that he was "surprised" and "disappointed" by the judge's ruling.

"There will be an appeal, based upon what we believe are errors in the judgment," he said.

Brian Beresh said he thinks the court was in error for failing to reconstruct the events surrounding the disappearance of Lyle and Marie McCann as well as Travis Vader's role. Beresh said he will be appealing the decision. 1:00

In a statement outside the courthouse, Bret McCann thanked the RCMP and the Crown for their hard and diligent work on the case.

"My parents had a very long and happy life together," McCann said. "They were kindred spirits, married in 1952, they loved to be together. It is so so sad that my parents didn't live to fully enjoy their golden years, did not live to see their great-grandchildren. They and us were robbed of this great happiness. We are thrilled that justice has been served."

The RCMP issued a statement Thursday thanking Justice Thomas for "his thorough review and assessment" of the evidence.

Couple disappeared more than six years ago

Speaking Thursday, Bret McCann thanked the RCMP and Crown for their diligence throughout the investigation into his parents' disappearance. 3:11 The case has gripped the city since July 2010, when the elderly St. Albert couple mysteriously disappeared after starting a summer road trip to B.C. Their bodies have never been found.

The case has seen a series of legal twists and turns that caused court proceedings to drag on for years. Vader was 38 when he was first taken into custody. He is now 44.

At the centre of everything, the outspoken accused man has badmouthed the RCMP, proclaimed himself the victim of a witch hunt, and insisted that he is innocent.

The McCanns left their home in St. Albert, just outside Edmonton, on July 3, 2010, en route to B.C.

Surveillance video taken at a St. Albert gas bar that day shows Lyle McCann, 78, filling up his RV before hitting the road.

The couple was towing their Hyundai Tucson SUV, which would later become a key piece of evidence in the trial.

Lyle McCann, 78, and his wife, Marie, 77, were last seen alive in July 2010. (CBC)

Family offered $60,000 reward

When the McCanns didn't show up in B.C., relatives began an emotional and public campaign to find them. A billboard with the couple's faces and a $60,000 reward offer was erected on the Yellowhead Highway east of Edmonton. It stayed there for six years.

Crown prosecutors have argued the McCanns never made it to B.C. According to the prosecution, they were killed near Highway 16, somewhere around Peers, Alta., while Vader was trying to steal from them.

Their motorhome was found in flames at the Minnow Lake campground near Edson, Alta., two days after the couple left on their road trip. Their SUV was found several days after that. The McCanns' bodies have never been found.

After the flames were put out, this was all that was left of McCann's motor home. (CBC)

RCMP quickly zeroed in on Vader as a suspect. At the time, he was a drug addict with no fixed address and a lengthy criminal record for petty crimes.

Vader had so many outstanding charges that officials were able to keep him in custody without charging him in connection with the disappearance of the McCanns.

It took almost two years before Vader was charged with two counts of first-degree murder. Almost two years after that, Vader filed a $1-million wrongful prosecution lawsuit against RCMP officers, Crown prosecutors and jail guards.

Soon after, the Crown stayed the murder charges. Typically, the Crown has one year to resurrect the charges if new evidence comes to light.

Nine months later, the Crown reinstated the charges.

Case built on DNA evidence

Travis Vader, centre, and his lawyer, Brian Beresh, arriving at the Edmonton courthouse Tuesday morning for the beginning of a murder trial expected to last six weeks. (CBC)

The Crown's case relied heavily on DNA evidence that tied Vader to the McCanns' SUV.

During the trial, which began on March 7, an expert witness called by the Crown testified that Vader's DNA was found on a can of beer in the SUV. The court also heard that Vader's blood was found on the centre armrest and on the front passenger seat and steering wheel.

Among the 208 exhibits entered during the trial, the Crown produced cellphone records that showed the McCanns' cellphone was used to contact Vader's ex-girlfriend several times in the hours after it is believed they were killed.

Prosecutors admitted their case was circumstantial, but insisted that when all evidence was considered, "the only rational conclusion that can be reached is that Travis Vader murdered Lyle and Marie McCann sometime on July 3."

Defence lawyer Beresh argued the DNA evidence was not enough to convict his client of murder. He said that evidence merely showed that Vader had some "incidental contact" with the vehicle. Beresh suggested the accused could have leaned into the SUV and sneezed, or been in contact with someone who later climbed into the SUV.

He argued the court would have to consider "the very real possibilities that Mr. Vader discovered the SUV and cellphone together and abandoned, after the true killer had detached the motor home."