The man described by police as a person of interest in the disappearance of five-year-old Nathan O’Brien and his grandparents has a link to the family and once operated an illegal drug lab on the property now being searched by authorities.

Calgary police and RCMP investigators have spent the weekend searching a rural property in Airdrie in connection with the hunt for O’Brien and his grandparents, Alvin and Kathy Liknes, who went missing from the couple’s Calgary home a week ago.

Police were summoned to a farm in the rural northeast corner of Airdrie on Friday night after someone linked it to a green Ford pickup truck similar to one seen in the Liknes’ neighbourhood on the night they disappeared.

Investigators took a man at the acreage in for questioning, but released him Sunday without any charges — though police added he remains a person of interest and they are continuing their search of the property.

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The Herald has learned the man questioned by police is Douglas Garland, who once served a 39-month federal prison sentence for drug trafficking.

Douglas Garland is in his early 50s. His sister is in a common-law relationship with a member of the Liknes family. Their parents, Archie and Doreen Garland, own the property being searched by police. Land title documents show the family bought the Airdrie land in 1973.

This weekend’s police search isn’t the first time authorities have descended on Archie and Doreen Garland’s farm: in October 1992, police uncovered a drug lab hidden inside a shed on the property.

Although police found no finished product, the lab contained a large quantity of chemicals used to make illegal synthetic drugs like methamphetamine.

Police charged Douglas Garland in connection with the operation, but he disappeared soon after and evaded authorities for seven years.

Authorities found Douglas Garland in 1999, thanks in part to a tipster who contacted police after seeing his picture on an RCMP “most wanted” list online.

Douglas Garland was living in B.C.’s Lower Mainland and working as a chemical mixer at the B.C. Institute of Technology when police found him. He managed to evade detection by stealing the identity of Matthew Kemper Hartley, a 14-year-old Cardston boy killed in a car crash in 1980.

At Douglas Garland’s trial, court heard he was a genius who studied science at the University of Alberta and studied to be a doctor. He left the program before earning a degree.

Douglas Garland’s time on the lam was the subject of a bizarre epilogue years later, when he fought the federal government in court over employment insurance benefits.

Douglas Garland had collected employment insurance benefits after getting fired from Can Test Ltd., a Vancouver laboratory firm where he worked between 1992 and 1997. The government later ruled that his earnings weren’t insurable because worked under a false identity.

Douglas Garland appealed that decision to the Tax Court of Canada — and won, following a trial where he represented himself.

A written decision by Justice Campbell J. Miller in 2005 said Douglas Garland was a “troubled man,” who had attention deficit disorder and whose exit from university was precipitated by a mental breakdown.

“It was clear he was agitated throughout the trial, but it was also apparent that he was an intelligent individual,” Miller wrote.