A suspect is facing three murder charges in the disappearance of five-year-old Nathan O’Brien and his grandparents, Calgary police announced Monday.

Chief Rick Hanson said no bodies have been found but mounting evidence has left police “absolutely convinced” O’Brien and grandparents Kathryn and Alvin Liknes, who vanished together on June 29, are dead.

A man was arrested early Monday morning at a property in the Airdrie, Alta. area and remains in custody. He’s facing two counts of first-degree murder in the deaths of the grandparents and one count of second-degree murder in the death of the boy.

His name won’t be released unless the charges are approved.

Hanson described the weeks-long investigation as "extremely challenging and heart-wrenching,” and offered condolences to the young boy’s parents, Jennifer and Rod O’Brien, and all members of the Liknes family.

“I can’t imagine how difficult and painful the last two weeks have been,” he said.

Police are not commenting on the evidence they’ve gathered but said they concluded the trio had met a grim end during a daily meeting of investigators Sunday.

“It was clear at that point this was no longer a missing persons investigation, this was a homicide investigation,” Hanson said.

More than 200 officers, investigators and analysts have contributed to the case, and more than 900 tips have been received from the public.

Police are asking people to continue coming forward with any information they have, and for rural land and business owners in the area to search their properties for anything suspicious.

O’Brien was at his grandparents’ house for a sleepover when the trio went missing. His mother arrived to collect him in the morning and found the home empty.

Hanson wouldn’t confirm whether the suspect arrested is Douglas Garland, who lives with his parents in Airdrie and has been identified as a person of interest in the case.

He was arrested earlier this month on unrelated charges and released.