Volunteers from three provinces and at least one U.S. state have come together near Airdrie, Alta., to scour the rural area for any signs of five-year-old Nathan O’Brien and his grandparents, Kathy and Alvin Liknes, from Calgary. 

About 150 people from Alberta, Saskatchewan and B.C., as well as one traveller from Minnesota, combed meticulously through a search area defined by organizers of the civilian-led effort after a confidential phone call with police.

Calgary police have laid murder charges against 54-year-old Douglas Garland, who was initially questioned by police as a "person of interest" during the early stages of the investigation and arrested on Monday.

Kathryn Liknes, Nathan O'Brien and Alvin Liknes

Nathan O'Brien, centre, and his grandparents, Kathy and Alvin Liknes, have not been seen since June 29. Their disappearance is now a homicide investigation. (Calgary Police Service)

Garland was charged with two counts of first-degree murder in the deaths of the Likneses, and one count of second-degree murder in the death of their grandson. Investigators say they believe all three are dead.

The spontaneous search came together Monday when a group of parents in Airdrie posted a call out for volunteers on social media.

"I’m a grandmother, so I’ve had a terrible feeling in my stomach for the whole two weeks since this happened," said Jaimie Tessier, one of the organizers.

A local Safeway grocery store donated food and other supplies, which were supplemented by donations from concerned residents.

"We’re a community that sticks together," said Greg Dyki, a Safeway manager. "Family needs to know where family is and that’s why we’re here."

Nathan O'Brien search party

About 150 people from three provinces and at least one U.S. state joined the search on Tuesday after a group of organizers took to Facebook to ask for volunteers. (Devin Heroux/CBC)

Kathy Keyes, a Minnesota woman who was passing through Alberta when she read the news about the Calgary family that has been missing since the end of June, told CBC News she felt she had to stop and help the search effort.

"It sounds like that little boy was caught in the middle, and that’s the hard part," she said.

Organizers of the civilian search party said they will continue their work on Wednesday, and won’t stop until police advise them otherwise.