09/27/2014 03:24 EDT | Updated 11/29/2014 05:59 EST

Nathan O'Brien Missing: Memorial Honours Kathy And Alvin Liknes

CALGARY - A memorial service paid tribute to two Calgary grandparents who police believe were murdered along with their grandson.

Alvin and Kathy Liknes (LIHK'-ness), and five-year-old Nathan O'Brien, haven't been seen since they vanished from the Liknes's home in June.

Photos of the couple, along with other family members, filled the entrance to First Alliance Church in Calgary on Saturday.

Alvin Liknes was remembered as an adventurer and a car enthusiast, while his wife was honoured as a generous and loving mother.

A separate service was held earlier this month for Nathan.

Douglas Garland faces two counts of first-degree murder and one charge of second-degree murder and a hearing to determine if there's enough evidence to warrant a trial is scheduled for May.

Investigators searched several properties near the acreage in Airdrie, north of Calgary, where Garland lived. The search lasted for weeks but the bodies have not been found.

Police have said there was evidence of a violent incident in the Liknes house but they have not disclosed a motive.

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Photo gallery Nathan O'Brien, Grandparents Missing See Gallery