Family members of a missing Alberta couple hope a memorial service held Saturday will help them move on, although they still don't know the full story of what happened to Lyle and Marie McCann.

"It's like a book with no end. We need to find an end to complete the story," one relative, Murray McCann told the service at a Catholic Church overlooking St. Albert, just north of Edmonton.

The McCanns, both in their 70s, vanished while on a trip in their motorhome more than a year ago and are presumed dead. Their burned RV was discovered shortly after they disappeared and RCMP said they were slain.

Mourners were handed envelopes with rose petals inside and were asked to deposit them in an urn that is being buried in a cemetery plot reserved for the couple.

Many who attended the service had only a passing acquaintance with the McCanns or didn't know them at all, but said they came because they felt moved by news stories of the exhaustive search for the couple.

Lyle and Marie McCann (CBC)

The courts recently declared the McCanns dead so that their family could start processing wills and dealing with the estate.

The RCMP said they have named a person of interest in their investigation but no arrests have been made.

During the service, family spoke about how Lyle McCann, who had been a long-haul trucker, told great stories and loved the smell of diesel. Marie McCann, meanwhile, was fondly remembered for her loud laugh and pie-baking prowess.

At one point mourners erupted into applause when two members of the search and rescue team that tried to find the McCanns were asked to stand.

Saturday's memorial was held on what would have been the couple's 59th wedding anniversary.

"I thank both of you for teaching me the importance of a devoted marriage, both of you adoring each other," said Nicole Walsh, the couple's eldest granddaughter, during the eulogy.

Last month, the RCMP said they had been leading searches in dense bush for the McCanns in a remote area near Lodgepole in west-central Alberta.

The investigation faced criticism in 2010 over its delays in getting started, as well as with the way staff at an RCMP detachment in B.C. failed to take contact information for a tipster.

A $60,000 reward is available for information that helps find the McCanns. Tips continue to come in, but no one has tried to claim the reward.