Police say the mother of Nathan O’Brien dropped him off at her parents' home at 10 p.m. Sunday night for a sleepover.
"She comes back at 10 this morning, notably sees that the house is not normally as it is and there's other things within the house that would lead us to believe that they did not leave on their own volition," said Calgary police spokesman Kevin Brookwell.
He said he couldn't give any details about what those things were and said the grandparents, 66-year-old Alvin Cecil Liknes and Kathryn Faye Liknes, 53, are not suspects.
"We're remaining optimistic that all three will be found safe and sound," Brookwell said. "Right now it's a suspicious disappearance of all three."
There are no custody issues with the family — the boy's parents are married and he is their biological son — and police have no history with the family, who are being co-operative, he added.
The grandparents' vehicles are accounted for, as are those of the family, which initially had police ruling out sending out an Amber Alert. But Brookwell said police and Alberta government officials then changed their minds.
"Normally when you look for the criteria for an Amber Alert, what was missing was a description about an abductor or a mode of transportation, which still exists, but given the other criteria, we do have a good description of the young lad as well as the grandparents, we decided we would put out an Amber Alert regardless of missing that one criteria," Brookwell said.
Nathan O'Brien is described as three feet tall, curly blonde hair and last seen wearing peach-coloured shorts and a blue-striped hoodie.
Alvin Liknes is six feet tall, 200 pounds with grey and blond hair and was wearing black shorts. Alvin has a distinctive walk. Kathryn Liknes is five foot, three inches tall, 120 pounds with reddish-brown hair and green eyes.
"It is a weird one," Brookwell said.
"We are doing neighbourhood inquiries as well to see if anybody saw or heard anything suspicious, but so far nothing, so that's why we are reaching out to the public."
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