07/13/2014 01:18 EDT | Updated 09/12/2014 05:59 EDT

Nathan O'Brien Amber Alert: Final search of Liknes home ends

After multiple searches of the home where three Calgary family members were last seen, police say they have ended the investigation into the Parkhill property and are returning it to the family.

Five-year-old Nathan O'Brien was last seen at the home belonging to his grandparents, Kathy and Alvin Liknes, on June 29. The three were discovered missing the following morning when Nathan's mother arrived to pick him up from a sleepover. 

Following an initial search of the house, police returned last weekend and extended the perimeter of their search area. On Saturday, they returned again for a final sweep but now say they have "released the home from police continuity," meaning it will no longer be the subject of police searches.

Calgary Police Service search teams are continuing their search of the Spyhill landfill on Sunday.

As well, police officers and the RCMP will continue combing a rural property in Airdrie, northeast of Calgary, that has been the subject of an enormous search effort over the past week.

The property belongs to the parents of a man who police say is a "person of interest" in their investigation.

Douglas Garland, 54, was taken from his parents' acreage to answer police questions about the case last Friday but was ultimately released from questioning on that matter.

Police kept him in custody and charged him with an unrelated count of identity theft and unlawful possession of a bank card.

Police say that charge is related to the recent use of the stolen identity of a 14-year-old Alberta boy who died in 1980.

Criminal history related to drug bust, stolen ID

Garland does have a criminal history, which includes drug trafficking and possession of stolen property after he was caught making ampethamines on his parents' acreage in 1992.

The then-33-year-old Garland fled those charges and a document from the Tax Court of Canada indicates he was later discovered living under that stolen identity in Vancouver.

He returned to Calgary after being discovered and pleaded guilty to several of the charges in connection to the drug bust and the stolen identity.

The identity theft charge Garland faces now is specifically in relation to the recent use of that stolen identity he used in the '90s.

His bail on that charge was set at $750 on Friday and Garland faces a set of restrictions, including reporting three times a week to a supervisor and once a week to police.

He must also live in transitional housing and can't return to his parents' Airdrie acreage while it is under police investigation.

'Bad blood' between Garland, Liknes

CBC News has also learned that Garland has several connections with the Liknes family.

His sister is in a common-law relationship with Alvin Liknes's son and investigators have also been looking into the business relationship between Garland and Liknes.

Sources say a business deal between the two went sour, leading to "bad blood," and Calgary police are investigating a patent dispute as part of their probe into the case.

Winter Petroleum, a junior gas company owned by Liknes, went bankrupt near the end of June — just days before the family went missing. 

Liknes had registered a patent for an apparatus that separates gas from water.

"There are some business issues that we are looking into," said Calgary Police Service spokesman Kevin Brookwell on Thursday. "I can't get into specifics about what these are and who was involved, what they look like or how many people were involved. But yes, we have got a number of people who are looking into that."

Court records also show that both Alvin and Kathy Liknes have declared bankruptcy in the past — Alvin in 1994 and Kathy just two years ago.

According to records, Liknes was involved in several civil lawsuits in the 1980s and early '90s. He was the defendant in two cases four years ago.