Members of the RCMP and Calgary Police Service are searching an acreage, northeast of Airdrie, as part of an ongoing investigation into the disappearance of five-year-old Nathan O'Brien and his grandparents, Kathryn and Alvin Liknes.

Police responded to the rural property, on Range Road 291, north of Highway 567, on Friday evening. The response followed a tip from the public indicating a vehicle matching the description of a suspect truck, which had been seen on closed circuit surveillance video recorded in the community of Parkhill, had been spotted.

A green Ford F150 pickup truck was located on the acreage by police.

On Friday night, one man was escorted from the property for questioning. The man is considered a person of interest.

“This is an investigative step,” said CPS Duty Inspector Joel Matthews. “We’re not certain that this is the fellow, we’re just following up on a tip. It may not lead to where we want it to lead, and this may not be related.”

Police have not confirmed that the pickup truck located on the acreage is the same vehicle which was recorded in Parkhill.

The investigation of the acreage includes uniformed members of the police service as well as search and rescue members. Police expect to remain on the property until Sunday evening or Monday morning as the size of the acreage presents challenges in the search for evidence.

Kathy and Alvin Liknes and five-year-old Nathan O'Brien were last seen at 10:00 p.m. Sunday, June 29 when Nathan was dropped of at the Liknes' Parkhill home. Police confirm a violent crime occurred in the Parkhill residence.

“Have we found the family? No, we haven’t," said Duty Insp. Matthews. "That’s why the Amber Alert is still out.”

Anyone with information about the disappearance is asked to contact the Calgary Police Service, 403-266-1234, or Crime Stoppers.