Marie Ann McCann and Lyle Thomas McCann were last seen July 3. (RCMP)

The family of missing Alberta couple Lyle and Marie McCann will soon be posting pictures of their parents on billboards along Highway 16, west of Edmonton.

The two billboards are part of the effort to find the couple who haven't been seen since July 3 and will advertise a $60,000 Crimestoppers reward. The billboards are to go up in the next few weeks.

"We see it in the news occasionally but we'd really like to leverage that and so we want to keep this top of mind to those people that are out in that area between Edson and Edmonton," said the couple's son, Bret McCann.

McCann said the family will continue their own search for the couple until the snow falls.

Lyle McCann, 78, and his wife, Marie McCann, 77, left St. Albert, Alta., on July 3 headed for British Columbia and have not been seen since.

Their burned-out motorhome was discovered in a campground near Edson, Alta., on July 5. The Hyundai SUV they were towing was found in nearby wooded area 11 days later.

RCMP searched a rural property near Nojack, Alta., last month as part of the investigation.

Travis Vader was named by RCMP as a suspect in the case, but no charges have been laid.

Vader remains in custody on other unrelated charges.