Calgary investigators say there are "still more questions than answers" as the search for a missing five-year-old boy and his grandparents continues. 

Police and RCMP are into their fourth day of an intense search at a rural property near Airdrie, just north of Calgary, looking for any evidence or clues. 

“The search will continue until no stone has been left unturned," said Calgary police spokesperson Kevin Brookwell. 

“We know there are certainly more questions than answers and we wish that we had those answers for you.”

Alta Missing Grandparents 20140705

Police investigators combed a hay field north of Airdrie, Alta., on Saturday in search of clues to the disappearance of five-year-old Nathan O'Brien and his grandparents. (Jeff McIntosh/Canadian Press)

Nathan O'Brien and grandparents Alvin and Kathy Liknes were reported missing more than a week ago.

Brookwell said police seized multiple items from the property. The property belongs to the parents of Douglas Garland, who was brought in for questioning Friday night. 

"I won’t go into what those were and where they were found but they have been seized and sent up to the crime lab," he said. 

Garland, who they call a "person of interest," was detained and spent the weekend talking to police about the disappearance of the three, who vanished from the home of Nathan's grandparents.

Garland was discovered on the acreage. Police were acting on a tip from the public about a green truck they had been looking for. The search for the truck led them to the site. 

Garland sketch

Douglas Garland during his first court appearance on Monday. (Sketch: Janice Fletcher)

"A truck was seized from this residence on the weekend matching the description of a truck caught on CCTV in the Parkhill area," said Brookwell.

Officers searched through three separate fields around the Garland property and brought in a member of the canine unit to assist with police officers' shoulder-to-shoulder searches. 

"Right now we’re looking at an area that’s several square kilometres," said Garrett Woolsey, the RCMP commander of the special tactical operations team involved in the search. 

"We are currently looking for evidence in relation to a missing persons case. That’s why we’re using so many officers." 

Investigators say the Amber Alert remains active. 

'Person of interest' has criminal record

Garland appeared in a Calgary court Monday to face the new charge of identity theft via closed-circuit television, and was expressionless and leaned against a wall as the charge was discussed. He will be back in court Wednesday. 

A homicide detective and Nathan's father were also in court. The father did not talk to reporters.

Garland has a criminal history, including drug trafficking and possession of stolen property after he was caught making amphetamines on his parents' Airdrie acreage in 1992.

In the early 1990s, Garland was convicted of stealing the identity of Matthew Kemper Hartley — a 14-year-old Alberta boy killed in a car crash in 1980. The charge laid against him this past weekend relates to another, more recent incident in which Garland allegedly used the boy's identity again. 

Garland was released from questioning specifically in regards to the Nathan O'Brien disappearance, but remained in police custody in relation to the latest charge of identity theft he now faces.

Garland has a connection to the Liknes family through his sister, who lists Nathan's parents, Rod and Jennifer, as well as Kathy Liknes as "friends" on Facebook.

She also lists one member of the Liknes family as a niece.

Neighbours tie ribbons of hope to homes

On Monday evening, members of the Calgary church where he was baptized held a special prayer service for Nathan O'Brien and Kathy and Alvin Liknes. It was attended by the family of the three.

Prayer vigil

The O'Brien family attended a prayer service Monday for their missing son, Nathan, and his grandparents. (CBC)

Rev. Julian Studden said the church community is deeply affected and concerned.

"They are feeling hurt that such a tragedy can happen to a boy like Nathan, and they have a heart of compassion and they feel like it's their own little one," he said.

Studden said the community is holding nine days of special prayers. Known as the novena, the vigils began Friday.

O'Brien and his grandparents were reported missing June 30,  after Nathan's mother arrived to pick up her son from a sleepover at the Likneses' Parkhill house. The family had been helping out with an estate sale the Likneses were holding ahead of a planned move to Edmonton.

As well as the prayer sessions, Parkhill residents are now tying green ribbons to their homes in a symbol of hope and support that the Parkhill Stanley Park Community Association says is meant to increase awareness and express hope for the safe return of Nathan and his grandparents.

Kathryn Liknes, Nathan O'Brien and Alvin Liknes

Nathan O'Brien, centre, and his grandparents, Kathy and Alvin Liknes, have not been seen since Nathan's mom left the home of the couple the night of June 29. (Calgary Police Service)

Police are still looking to speak with anyone who attended the estate sale on June 27, 28 and 29.

Investigators estimate between 200 and 300 people went to the sale, but they are trying to get an idea of what was purchased and what remains in the home.

They say there was no sign of forced entry into the home, but that blood found inside confirms that a violent incident did take place.

Police could not say who the blood belonged to, only that it signalled someone had been "in medical distress."

The forensics unit also examined "marks" along the outside of the house, but police could not confirm whether those marks are blood.

Police have a number of theories as to what took place, but aren't making those public.

Anyone with information about the case can call the Calgary Police Service at 403-266-1234 or Crime Stoppers anonymously at 1-800-222-8477.

Airdrie acreage search