Travis Vader, pictured in a courtroom drawing from July 27, has been called a person of interest in the disappearance of Lyle and Marie Ann McCann. (CBC)

Travis Vader, described by police as "a person of interest" in the disappearance of an Alberta couple, was represented by his lawyer during an Edmonton court appearance on an unrelated case Tuesday.

Vader remained at the Edmonton Remand Centre because he was supposed to make a video appearance at another courthouse later in the day. His lawyer asked that the case be put over for two weeks.

Bret McCann, the son of Lyle and Marie Ann McCann, who disappeared more than a month ago, was in court with his wife, daughter and son-in-law in hopes that Vader, 38, would see them and be persuaded to help find his 78-year-old father and 77-year-old mother.

"We wanted him to see us as a family, and kind of make almost a silent appeal for him to come forth and, you know, if he does have information, to own up to it and let the police know," McCann said.

The RCMP have said they believe Vader, who is being held in custody on unrelated matters, has information about the McCanns or had some involvement with them, although he has not been charged with anything related to the couple's disappearance.

Vader made a court appearance on another matter via video on Monday in Evansburg, Alta., which is between Edmonton and Edson. He has other court dates scheduled for Wednesday, Thursday and Aug. 16.

Vader faces a number of charges, including some related to theft, firearms and arson.

The family of Lyle and Marie Ann McCann has not heard from the couple since they left home on July 3 for a camping trip to B.C. (Canadian Press)

The McCann family met with the RCMP this week to get an update on the investigation into the couple's disappearance, Bret McCann said.

Police have only interviewed Vader once, McCann said.

"They're waiting for some evidence to become clearer before they meet with him next," he said. "They're analyzing forensic results from the motorhome and the SUV and these things take time, I guess."

The last reported sighting of the McCanns was on July 3, shortly after they left their home in St. Albert, Alta., for a camping trip to B.C. in their motorhome, which was pulling an SUV.

Their burned-out motorhome was found two days later at a campground near Edson, Alta., about 200 kilometres west of Edmonton. The SUV was found two weeks after they disappeared, also near Edson.

Vader and another man were arrested July 19 in Niton Junction, about 150 kilometres west of Edmonton. Both were interviewed about the disappearance of the couple.

The other man, who police have not named, was released without any charges.

The McCanns were last reported to have been seen getting gas on July 3, shortly after they left their home in suburban Edmonton on their way to the Vancouver area.

The couple's motorhome was found burned to a shell on July 5, but the missing persons investigation didn't begin until July 10, when their daughter reported them missing after they didn't meet her as planned at the airport in Abbotsford, B.C.