RCMP have confirmed Travis Edward Vader, 38, is a suspect in the case of a missing couple from Alberta. (RCMP)Travis Edward Vader is now considered a suspect in the case of missing Alberta couple Lyle and Marie Ann McCann, RCMP said Tuesday.

Police believe the disappearance of the McCanns was a result of foul play and previously identified Vader, 38, as a person of interest. He has been in custody in Edmonton since July 19, charged in an unrelated matter.

"It's the positive progress that we have made in the investigation which now validates Mr. Vader as a suspect," Sgt. Tim Taniguchi said at a news conference Tuesday morning at RCMP Edmonton's K Division.

It's an announcement that the family of the missing couple is viewing as a step in the right direction.

The McCanns were last seen getting gas on July 3, shortly after they left their home in St. Albert, Alta., on their way to the Vancouver area.

Two days later, the couple's burnt-out motorhome was found near Edson.

'This is bringing us a step closer to finding my parents and a step closer to ending this nightmare.'—Bret McCann

Vader and another man were arrested in Niton Junction, about 150 kilometres west of Edmonton.

Vader was interviewed about the disappearance of Lyle, 78, and Marie Ann, 77. The other man was released.

At this time, police said, they are not disclosing the details of what they think happened.

"In all types of investigations, we get information, and it's ongoing information from a number of different sources ... revealing the specifics of that information in regards to this specific case would be inappropriate because it could put the investigation at risk," Taniguchi said.

Taniguchi wouldn't confim or deny if there are any other suspects.

No charges have been laid.

McCann family 'pleased'

Bret McCann, the McCanns' son, said the police announcement is somewhat of a relief.

"Both myself and my family are pleased that the investigation has really progressed to this stage," McCann told CBC News.

"We think that this is bringing us a step closer to finding my parents and a step closer to ending this nightmare."

McCann said it is his family's understanding that police don't have any direct knowledge of where his parents are.

"We're staying optimistic," he said. "My family is very close-knit."