Douglas Garland, who is 54, is charged with first-degree murder in the deaths of Alvin and Kathryn Liknes, and second-degree murder in the death of five-year-old Nathan O'Brien.
No bodies have been found but police say there is sufficient evidence to conclude the trio have been slain.
On Tuesday night, relatives gathered at a park across the street from the O'Brien home to release hundreds of green balloons in memory of the little boy and his grandparents, a tribute that was repeated in communities across the province.
Nathan's mother and father, Rod and Jennifer O'Brien, wept and held each other and their son Luke as they watched the ballloons fly away.
Jennifer's brother, Jeff Liknes, says he has not given up hope that his parents and nephew may still come home safely.
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