07/15/2014 09:14 EDT | Updated 09/14/2014 05:59 EDT

Douglas Garland charged with murder of Nathan O'Brien, grandparents

Douglas Garland was charged today with first-degree murder in the deaths of Calgary residents Kathy and Alvin Liknes, as well as second-degree murder in the death of the couple's five-year-old grandson Nathan O'Brien.

The charges come a day after police announced that the search for the the family had become a triple murder investigation. Police believe there is enough evidence to say they have been murdered, but their bodies have not been recovered.

Garland was arrested Monday, and escorted to a Calgary police station late at night. He had been considered a "person of interest" up to that point, having been arrested previously on charges unrelated to the missing family case, and then released.

The 54-year-old hung his head and said nothing to the cameras on his way into the Calgary arrest processing unit.

The family disappeared more than two weeks ago. Police have not found their remains despite a massive search with more than 200 police officers working around the clock and following up on more than 900 tips from the public.

"There's already been extraordinary search efforts as large as I've seen in this country in a long time," said retired homicide investigator Dave Perry on Monday.

"And now that the bodies haven't been recovered I think that the search is going to expand and who knows where it's going to take them."

Calgary police continue to ask for the public's help. Rural property owners, including oil companies and businesses, are still being asked to search their properties for anything suspicious.