Investigators in British Columbia's southern Interior took a woman into custody Tuesday afternoon in connection with the homicide of a 12-year-old autistic boy in Grand Forks.

The body of John Fulton was found in the Gables, a subsidized condo complex where he lived with his mother and sisters, late Monday night. RCMP officials have not said how he died, or when.

Hundreds of residents searched for Fulton, described as a happy, high-functioning autistic child, after he disappeared from the steps of his family home Saturday afternoon.

Investigators announced Tuesday afternoon that they had taken Kimberly (Kim) Ruth Noyes, 42, into custody without incident. Noyes, who lives in the same condo complex, reportedly suffers from mental illness, including bipolar disorder and depression.

RCMP had said earlier that Noyes posed a threat to herself and possibly others because of her mental health.

Officers could be seen at a home in the condo complex late into Monday night.

Neighbour Theresa Paylor told CTV British Columbia Monday night the woman who lived in the residence was depressed.

"I've been talking with some neighbours of mine and no one's seen her outside the house in the last few weeks and she's kind of keeping to herself."

Paylor said the death has shaken up the tight-knit community.

"It's unnerving. We're all parents here."

Mayor Brian Taylor agrees.

"We pride ourselves on being a safe community. Children here walk to school and parents have a sense of comfort, and I think we're going to lose that," he said.

"Given the smaller size of the community of Grand Forks, the Fulton family will continue to receive support from it during this horrific turn of events," Vermuelen said.

"The RCMP along with the community of Grand Forks will continue to provide this support and assistance to the Fulton family."

Grief counsellors have been brought in to help those who know the family.

Grand Forks is a community of around 5,000 residents sitting on the Washington State border about 600 kilometres east of Vancouver.

Anyone with information about the investigation is asked to call their local police detachment or the Grand Forks non emergency line at 250-442-8288 or Crimestoppers at 1-800-222-8477. Anyone who sees Noyes is asked to call 911.

With files from CTV British Columbia's Kent Molgat and Penny Daflos, and The Canadian Press