Police have wrapped up the search for evidence at a southeast Calgary landfill in the disappearance of Nathan O’Brien and Alvin and Kathy Liknes and are focusing their efforts on an acreage north of the city and the Spyhill Landfill site.

The search for the missing Calgarians in now in its 12th day and officers continue to work tirelessly to determine what happened to the five-year-old and his grandparents.

Officers have completed a search of the East Calgary Landfill and officials say they will decide later if they need to also conduct a search at the Shepard Landfill.

On Friday, search teams were back at the Spyhill Landfill in northwest Calgary and at the Garland farm northeast of Airdrie.

Police also have a tactical unit at the Airdrie acreage to deal with chemicals that were found on the property.

"All I can say is it is considered dangerous and flammable in nature so we're taking precautions at that site for the officers who are out there conducting the search and handling or looking at those chemicals," said Kevin Brookwell of the Calgary Police Service.

Police are asking people who own land near the Airdrie acreage to check their properties for anything unusual and officers are going door-to-door in the area.

"You know your property better than anybody else. You can see if anything is missing, if anything has been disturbed if there’s anything odd, tire tracks, absolutely anything that’s out of the ordinary. We would rather hear about it and follow up on it to see if there's any relevance or not and that’s what we’re asking folks to do," said Brookwell.

Brookwell says people in the Parkhill/Stanley Park area near the Liknes home should do the same.

"Check your property, either in the city or rural, businesses, some of the oil companies have wellheads, things like that, sites that are not checked on a regular basis. We're asking take the time, send folks out, have a look around if anything suspicious, just let us know." said Brookwell.

Police are still looking to talk to anyone who may have attended an estate sale at the Liknes home on the weekend of June 28th and 29th.

Anyone with information is asked to contact police at 403-266-1234, by email at homicidetips@calgarypolice.ca, or via Crime Stoppers.