The Calgary skyline.John Lehmann/The Globe and Mail
An Amber Alert remained in effect across Alberta on Canada Day as police continue to search for leads in the perplexing disappearance of a five-year-old boy and his grandparents.
Nathan O'Brien was reported missing Monday morning when his mother went to pick him up after a sleepover at the grandparents' southwest Calgary home and they weren't there.
Police say that, based on things they found in the home, they don't believe the residents left voluntarily.
Investigators now confirm the family held an estate sale in the home over the weekend, but they say it's too early to determine whether it's relevant to the case.
They say they're looking to speak to anyone who was at the sale, but they say they don't have any significant leads.
Investigators have said that the grandparents, 66-year-old Alvin Cecil Liknes and Kathryn Faye Liknes, 53, are not suspects.
"Obviously we want to find them as soon as possible," Inspector Keith Cain said Tuesday about the missing trio.
"We have the only scene that we're aware of right now contained, and we're going through that doing our best to find whatever clues may be there," he continued.
"But the bottom line is we don't know where these people are right now."
Police updated their description of the boy on Tuesday, noting that the child's eyes are brown and not blue.
Investigators have not disclosed what was found in the home that suggested the residents were forced to leave.
Police have said 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.
The grandparents' vehicles are accounted for, as are those of the family.
Nathan O'Brien is described as three feet tall with curly blonde hair, and was 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.