Nearly one year later and police have yet to solve the mystery of what happened to Lyle and Marie McCann. The St. Albert couple disappeared on July 3rd after leaving in their RV to visit family in British Columbia.

CTV News has uncovered some of the bizarre coincidences in a case that's proved to be extremely difficult for police to solve.

The only person of interest in the case, Travis Vader, is currently behind bars on unrelated charges.

The couple fuelled up after leaving St. Albert, then made a stop in Gainford, west of Edmonton.

"I asked where they were going and she said they were going to Abbotsford to meet their daughter," said store owner Oksana Kulhawy.

Then, they were never seen again. The couple's burned-out motor home was found on July 5th near the Minnow Lake campground approximately 35 kilometres southeast of Edson. And on July 16th, their green Hyundai SUV was located deep in the bush about 30 kilometres east of Edson near Carrot Creek.

Investigators say Vader is still the suspect in this case, and add it's beyond doubt that the couple met with foul play.

"It has been a year since we entered into this investigation and we are now solidly into a homicide investigation," said the lead investigator in the case, Don Campbell.

The couple left city limits just after 10 a.m. on July 3rd, and by noon, they had disappeared.

Police were not fully on the case immediately, and the couple's burned-out RV wasn't initially investigated fully. Investigators say part of the problem isn't just the fact they have no human remains, but also what is likely the primary crime scene in this case, as the RV was destroyed at Minnow Lake.

"Most, but not all homicide investigations, we start out with a crime scene and bodies. In this case, we have no bodies and in this case we believe our crime scene was a mobile crime scene that has been burned," said Campbell.

And as the search continues, with one as recent as last weekend west of Lodgepole, the couple's son says he knows his parents are homicide victims.

"I've gotta think there were was multiple people involved, maybe not in the initial encounter, but in the cover-up afterwards," said Bret McCann.

He believes a drug culture west of Edmonton has played some role in his parents' disappearance. He still believes Vader is the person who knows details.

"It's probably a lot of fear of coming forward, either fear of violence being committed against them, or fear of a loss of their supply," said Bret.

Surveillance video of a business west of Edmonton shows Vader purchasing some beer around the same time police were on the lookout for him.

And despite that video, there was talk at the time that Vader was making every effort to avoid capture. Sources have shown CTV that he was hiding at a shelter in the woods at the time, and had friends bring him food and supplies.

Multiple sources now tell CTV about Vader, his circle of friends, and addictions to crystal meth. One person in that circle, Teri Johnson, was already on the RCMP's radar after a big drug bust west of Edmonton a few years back.

Multiple sources have told CTV News they believe Johnson may have held key information about the missing couple. But what she may have known will never be learned because exactly one month after the McCanns went missing, she died in a head-on crash near Drayton Valley.

Police say speculating on her knowledge does nothing to further their investigation.

"It is factual she was killed in a motor vehicle collision and that's all I can do with that," said Campbell.

Loved ones of Terry McColman say in the past year, he was questioned by police multiple times, and had his property searched because he and Vader were close friends at the time the couple disappeared. McColman died last month, apparently of a heart attack.

Police now say they had interest in him.

"Terry McColman is a person who was spoken to, Terry McColman has since passed away as well," said Campbell.

But Johnson and McColman had more in common than drug problems and Vader. Both were in the company of the same person when they died. According to multiple sources, that man is well known to Vader. And a coincidence even more bizarre, is that same man was living in St. Albert last summer, just 800 metres from the home of Lyle and Marie.

One man says he witnessed plain clothes officers in the neighbourhood, having a heated discussion with that man last summer.

"They must have spent an hour with him, and then he went back in the house, appeared somewhat irritated," said the man.

And when CTV mentioned the name of that man to police, they declined to comment.

"I'm not going to get into specific individuals in the investigation or specific evidence," said Campbell.

The couple's family is being assured by police that they are pulling out all the stops to solve this case.

The couple's granddaughter, Nicole Walshe, recently gave birth to a little girl, who will never get a chance to meet her great-grandparents.

"I try to dress Chantelle in bright colours and tell her your grandma would have loved this colour and I can see a little bit of red in her hair and my grandma loved red hair... telling her those little memories and talking about grandpa and grandma, that's all I can do," she said.

CTV's lawyers have instructed us not to name the man who lived near the McCanns last summer, given the fact that police have neither called him a person of interest nor a suspect in the case. Investigators will not confirm or deny he is part of their investigation.

A $60,000 reward is still being offered for information about the couple's disappearance. You can call Crimestoppers at 1-800-222-TIPS.

With a report from CTV's David Ewasuk