Al and Rita Chretien left Penticton, British Columbia, on March 19 and never arrived at their destination.
The couple, who attend the Penticton Church of the Nazarene, was last seen in Baker City, Oregon. The Chretiens planned to attend a trade show in Las Vegas, Nevada.
This past weekend Oregon law enforcement officers assisted the Royal Canadian Mounted Police in a search of the area for the Chretiens, but found nothing.
Al, 59, and Rita, 56, who own a small excavation company, stopped at a Yamaha dealership in Baker City, Oregon, the day they left British Columbia. Police have security camera footage of the Chretiens at a convenience store - the last time anyone saw them.
The couple used their credit card to pay for gas at the convenience store, which is the last active purchase on their credit cards, and their bank accounts and cell phones remain inactive.
This has led investigators to consider robbery may have nothing to do with the couple's disappearance, but they haven't ruled out foulplay, police said.
The inactivity with their accounts also makes it unlikely the couple changed plans and went somewhere else without informing family and friends, police said.
Friends of the couple helped police search more than a week ago and learned the Chretiens planned to visit a nearby interpretive center. The couple never signed the guestbook at the center, and investigators wonder if the couple even made it to that destination.
Weather conditions cooperated this last weekend, which allowed an aerial search of Baker County. An Oregon State Police airplane flew Highway 86, the Hells Canyon corridor, the lower portion of Burnt River Canyon, Highway 245 over Dooley Mountain, and areas around Highway 7, Baker City police said.
The search extended through Baker, Malheur, Grant, and Harney counties in the eastern and southeastern portions of the state. More than 40 law enforcement officers and 18 search and rescue volunteers from six separate Oregon agencies traveled more than 3,500 miles of state highways and county roads during the search, police said.
The Royal Canadian Mounted Police assigned two investigators to the missing person case, and they were in Baker City for six days, but had to return to Canada after exhausting all available leads.
"The Chretien family and friends have been extremely touched and moved by the huge response that the disappearance of Albert and Rita Chretien has generated on both sides of the border. We wish to particularly thank all of the various law enforcement agencies in the United States and particularly in Baker City as well as the RCMP in Canada," Albert and Rita's family said in a prepared statement.
"Since March 31, friends and family have witnessed an around the clock effort to find them," they added. "We want to thank all the citizens of Oregon who have been praying, searching, and providing tips to the authorities. It has moved us to tears at times with how willing people have been to stop their own lives to help out."
Authorities will scale back the overall search; however, police patrols throughout eastern and southeastern Oregon will continue to watch for any sign of the couple and their vehicle, a light brown, 2000 Chevy Astro minivan.
The Chretiens' friends and family continue to hope and have scoured thousands of miles of highway for the missing couple.
"You're looking for tracks that go off the side or trees that have been damaged," Al's brother-in-law Tim Hoving told CTV Television Network
Their search turned up a few leads, but the couple remains missing.
"Al and Rita would have done that for us if we were on the other side of the fence," family friend Armand Gregoire told CTV.
Al's sister Lorraine Hoving says she isn't ready to give up.
"You never lose hope that you can find them and you can still find them alive. It would take a miracle now, but we still believe in miracles," she said.