RCMP in southeastern B.C. are treating the case of a three-year-old boy who has been missing since Tuesday as an abduction by a stranger, with an Amber Alert remaining in effect and the search continuing for a person of interest.

Kienan Hebert was last seen when his family put him to bed Tuesday evening at his home in the southeastern B.C. community of Sparwood, located about 600 kilometres east of Vancouver, near the Alberta border.

He was reported missing about 9 a.m. MT Wednesday.

Although the boy has a history of wandering in his sleep, "we're considering this as an abduction case — a stranger abduction," RCMP Cpl. Dan Moskaluk told CBC News early Thursday.

Kienan is described as a red-haired Caucasian boy and was last seen wearing a blue pair of Scooby Doo boxer shorts. It is also believed he was carrying several blankets.

Randall Hopley is sought as a person of interest in Kienan Hebert's disappearance. RCMP

Police are looking for Randall Hopley, who is not related to the Hebert family, as a person of interest. He is described as:

• Age 46.
• Brown hair.
• Hazel eyes.
• Caucasian.
• Having a birthmark along his hairline.

They are also looking for his brown 1987 Toyota Camry with the B.C. licence plate 098RAL, and urging the public to call 911 immediately with any information.

It was at first speculated that Kienan might have wandered into the night while asleep, Moskaluk said late Wednesday.

"Nothing has been ruled out but certainly we are considering foul play of course in this matter, but again we remain hopeful and optimistic in thoughts with the family that we're going to have a positive outcome to this effort so far in locating the child unharmed and well," he said.

Search-and-rescue officials as well as dozens of volunteers then began scouring the area, with a police dog unit and RCMP helicopter called in to conduct a search of the ground, Moskaluk said.

Boy has sleepwalking history

During that time, members of the RCMP's Southeast District Major Crime Unit, Cranbrook RCMP and the local Elk Valley detachment were examining the scene of the disappearance, including dusting parts of the boy's home for fingerprints, to determine what may have happened to Kienan, said Moskaluk.

"There's a history that Kienan does sleepwalk, but in past incidents, he's never exited the house. Other than that, there's not much else [to explain his disappearance]."

Randall Hopley was reported to be driving a car like this 1987 Toyota Camry. RCMP

Officials decided to look at issuing an Amber Alert around 5:30 p.m. Wednesday.

An Amber Alert is a warning system adopted in several countries, including Canada, that quickly tells the public through media and electronic highway signs of abducted children who are in imminent danger.

Moskaluk couldn't say why investigators identified Hopley as a person of interest.

He noted that Hopley is currently on probation with conditions and lives in the Sparwood area. Police are encouraging Hopley, as part of their message to the public, to speak to investigators.

Hopley was sentenced to two months in jail and two months of probation after he was convicted of an assault in April 2010, court records indicate. He also has a history of convictions for break-ins.

The RCMP says stranger abductions are a rare occurrence. Most abductors are generally known to the child.

With files from The Canadian Press