A suspect in the disappearance of a five-year-old Calgary boy and his grandparents will be charged with two counts of first-degree murder and one count of second-degree murder.

Police would not identify the suspect until he is formally charged, but CTV News has learned that Douglas Garland, 54, was arrested for the second time and there are no other suspects.

Nathan O’Brien and his grandparents, Alvin and Kathy Liknes, vanished on June 30 and have not been seen since.

 Police arrested a man on Monday at about 1:30 a.m. in the Airdrie area but charges have not yet been laid so the man cannot be officially identified. The man was led into the arrest processing unit downtown late Monday night and charges are expected.

Calgary Police Chief, Rick Hanson, provided an update to the media on Monday afternoon and confirmed that the case is now a homicide.

“We have to assume that, whatever that is, whatever the small likelihood is, that someone, somewhere, was keeping one of those people alive so we will always err to the side of caution, so we meticulously put this file together, until yesterday afternoon and in meeting with the Crown prosecutor and in reviewing all the evidence in its entirety, the decision was reached that this is now a homicide investigation and the charges would be appropriate against the accused individual that will be named later,” said Chief Hanson.

The man is in custody and police say two counts of first-degree murder and one count of second-degree murder are pending.

Hanson says they have not recovered any bodies but that the evidence collected points to their deaths.

“The bodies of the victims have not been found and we continue to ask people to come forward with any information they may have,” said Hanson. “The preponderance of evidence is such that it has led our investigators to believe that they are dead.”

Hanson says they are very confident in the strength of the evidence in this case.

"There is no single piece of evidence that would be what people would like to think was the smoking gun. Investigations of this magnitude are literally dozens of dozens, over 200 people each involved, officers each involved in doing a particular part of the investigation and meticulously pulling pieces of information together that supports a charge in this case so if you're looking for one piece of information, let me tell you that when the evidence comes forward you will see the meticulousness the thoroughness of this investigation," said the Chief.

He says over 200 officers were involved and that they received more than 900 tips in the case.

“Everybody, every officer, every person, every analyst involved in this investigation, contributed in some small way to pulling these pieces of information together that finally, as of yesterday, removed all doubt that it was a missing persons file, supported our now firmly held belief that it’s a homicide and led to the charges.”

Hanson says the first-degree charges relate to Alvin and Kathy Liknes and the second-degree murder charge relates to Nathan O’Brien.

"First-degree murder charges are generally laid when you can show pre-intent, somebody formed the intent and in second-degree murder charges, that pre-intent, the intent to commit the act, may not be there. Insufficient grounds to justify a first-degree murder charge."

Police will continue to investigate and say they will do everything they can to find the bodies.

"Our efforts to locate the bodies of the three deceased is obviously a big part of what we're hopeful, at some point in time, to be able to address," said Hanson. "I'll always remain optimistic that we will be relentless in pursuing every lead."

The family has been notified and Hanson says they are devastated. "Unfortunately with the laying of the charges, we've taken that hope away from the family so they are devastated."

The president of Cenovus released a statement of condolence on Monday saying…

All of us at Cenovus are deeply saddened by the recent developments in the search for Nathan O'Brien and his grandparents Kathy and Alvin Liknes. My thoughts are with Rod and Jennifer O'Brien, who work for Cenovus. It has been a heart-wrenching two weeks for them, and I can only imagine how devastating this news has been. On behalf of everyone at Cenovus, I offer them my deepest sympathy and condolences.

Brian Ferguson

Cenovus President & Chief Executive Officer

People who live in Parkhill near the Liknes home say they are saddened to hear the case has become a homicide investigation.

"It's every parents worst nightmare and to lose a child, nothing can compare to that loss and for the whole family we just pray for strength and for some peace down the road, that there can be some closure for them," said Maddy Taylor and Caroline Hart.

"Just wanted to come and pay our respects to the family. Extremely sad news," said Tim Taylor. "I have grandchildren their age and my heart goes out to them."

"I'm the same age as Alvin and Kathy's son and to think of losing my parents like that and my nephew, it's a nightmare, and we live just down the hill so to think it happened so close to home is really terrifying too," said Natalie Stevenson.

The Amber Alert that was activated in response to the family's disappearance has been discontinued.

Police are still asking people near the Airdrie farm to check their properties and to call them if they note anything out of the ordinary.