EDMONTON -- When Bret McCann last saw his parents nearly six years ago, they had their motorhome packed and parked in the driveway and seemed excited to be leaving the next day on a camping trip to British Columbia.

McCann testified Tuesday that he played some pool with his father in the basement of their home in St. Albert, a bedroom community north of Edmonton, on July 2, 2010. His wife and mother, after checking out some garage sales, came home with a bucket of fried chicken for supper.

McCann said his parents, in their late 70s, had been avid campers for decades but had recently stopped their winter trips to the United States because of increasing health insurance costs. They were eager to get back out on the road, he said.

They were going to meet other family and deliver a present to one of their great-grandchildren in Vancouver.

"They were looking forward to their trip," McCann told the judge hearing the first-degree murder trial of Travis Vader.

"I think they were kind of pumped ... quite positive."

Lyle and Marie McCann were last seen on surveillance video the next morning getting groceries and fuelling up their motorhome at a Superstore in St. Albert. Three days later, their RV was found on fire about 200 kilometres away near Minnow Lake west of Edmonton. An SUV they had been towing was found on a nearby rural property about a week later.

Their bodies have never been found.

Vader, 44, has pleaded not guilty in the deaths of the couple.

The Crown is arguing that Vader, once an oilpatch worker who supported a wife and seven children, had become a crystal meth user who was living in makeshift camps and was wanted by police on warrants.

The defence has told the judge that evidence will point to other suspects and there's not enough proof the McCanns are really dead.

Legal experts say that there's often a slow piecing together of evidence in murder cases with no bodies to prove a criminal death and rule out other possibilities. Those could include the alleged victims wanting to start a new life somewhere or committing suicide.

Bret McCann, the oldest of the couple's three children, testified that his parents were active and healthy. His father, a retired long-haul trucker, had some heart and vision problems. His mother's fingers had become twisted with arthritis and her memory "was starting to slip a bit."

McCann recalled his dad playing card games such as Rummoli with his mom to try to keep her mind sharp. He also said his dad was in great shape and had recently scrambled up on his roof to cut a tree branch.

His parents did own some guns, he said. His father had four rifles and shotguns, used years earlier for hunting ducks and gophers, and his mother kept a small Derringer pistol by her bedside after she caught a man looking in their window.

The couple never took the guns on camping trips, McCann said, and they were all found in his parents' home after they vanished.