07/15/2014 09:11 EDT | Updated 09/14/2014 05:59 EDT

Albertans release green balloons for Nathan O'Brien

Hundreds of Calgarians and people across Alberta released green balloons into the skies above the city Tuesday night in honour of Nathan O'Brien.

A Facebook group organizing the balloon release was started Monday after police announced that evidence has led them to believe five-year-old Nathan O'Brien and his grandparents, Kathy and Alvin Liknes — who have been missing for more than two weeks — have been murdered.

Douglas Garland, 54, was charged Tuesday with two counts of first-degree murder for the deaths of the Liknes' and one count of second-degree murder for the death of Nathan.