RCMP and Calgary Police investigators were searching the acreage, on a tree-lined driveway, just northeast of Airdrie, a bedroom community just north of Calgary.
"They are at the location as part of the investigation into the disappearance of Nathan O'Brien and Katherine and Alvin Liknes," Calgary Police Duty Inspector Joel Matthews said in a news conference Saturday evening.
Matthews said a green Ford F-150 truck matching the vehicle that was captured on video near the home was recovered and a man taken into custody.
"A man from that residence has also been taken in for questioning however it's too early to determine if the address, vehicle or man taken in for questioning are linked to the file."
Five-year-old Nathan O'Brien and his grandparents Alvin and Kathy Liknes disappeared from their Calgary home on Monday.
Calgary Police confirmed Friday that there was evidence that a violent incident took place in the home.
The Amber Alert issued on Monday remains in effect and Matthews said it's impossible to say at this point whether the boy and his grandparents are still alive.
"We don't know that. Really we're trying desperately to find out," he said.
"This is just an investigative step. It's not that we're certain this is the fellow. We're just following up a tip. Have we found the family? No we haven't and that's why the Amber Alert is still out."
Matthews said at this point the man, who was taken into custody late Friday night, has been cooperating "to a degree" and is considered a "person of interest".
The search was likely to take another 24 to 36 hours Matthews said.
About 20 police officers were walking side-by-side doing a grid search of a hayfield just south of the acreage. A similar search was done in the area around the Calgary home earlier in the day.
The grandparents were planning a move to Edmonton and then on to Mexico when they disappeared. They had held an estate sale the weekend before the disappearance.
Police have said there are no custody issues with the family _ the boy's parents are married and he is their biological son. Police have also said officers have no history with the family. All of the family's vehicles have been accounted for.
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