Volunteers who have spent three nights combing through fields near Airdrie, Alta. for three people missing and presumed dead have called off their civilian search after Calgary police said any assistance searching public property is no longer needed.

In a statement released Thursday afternoon, Calgary police said they “do not require assistance from the public in relation to searching public property, however we appreciate the outpouring of community support.”

A representative of the group, which had been scouring fields near Airdrie, said they will respect the police request and cease the search.

Investigators say they have a 30-day search plan in effect that is “intelligence-driven,” which can’t be “shared outside of law enforcement in order to protect the integrity of the investigation.”

The police search includes Calgary police officers, RCMP and provincially sanctioned civilian search organizations.

“The Service has and will continue to dedicate as many resources as necessary to complete what has become a highly sensitive, and complex, investigation,” the statement said.

They continue to ask private landowners and businesses to check their rural property for anything suspicious.

The volunteer group had called off their search Wednesday after a number of individuals posted negative comments on their Facebook page. The group also faced criticism that their search could compromise an ongoing police investigation. However, they resumed their search Thursday morning after dozens of people showed up to keep looking.

Earlier Thursday, volunteer Jamie Tessier told CTV News Channel that civilian searchers were not focusing on areas that police were combing, and were staying off private property unless landowners let them take a look.

"Obviously, the RCMP and the police have their areas that they're specifically looking into," Tessier said. "We're all adults, none of us would do anything to jeopardize this search. We are out there to aid them."

Douglas Garland has been charged with two counts of first-degree murder and one charge of second-degree murder in the deaths of Alvin and Kathy Liknes and their five-year-old grandson Nathan O'Brien, who've been missing since June 29.

The bodies of the victims have not been found, but Calgary's police say investigators they're presumed dead.

Alvin Liknes' son Allen said Wednesday, that the outpouring of support from the community has helped the family.

With files from The Canadian Press