RCMP study the scene of a fatal fire on the Shamattawa First Nation, where a home burned down Saturday but remains weren't discovered until Tuesday. (CBC)

The foster mother of the 11-year-old boy believed to have died in a fatal house fire in northern Manitoba's Shamattawa First Nation fears he may have been involved in starting the fatal blaze.

Mary Anderson told CBC News that the boy, Edward Redhead, was only with her for a few short months. She was told he was a gas sniffer when she agreed to take him in.

"When I first had him here he was distraught, like something was bothering him. Somebody was telling me that he was a sniffer but I took him anyway — took my chances," she said.

Redhead was in Anderson's care through the Awasis Child and Family Services Agency. During the Christmas holidays, Redhead was away from Anderson for a visit with his grandparents, who also lived in the reserve, about 750 kilometres northeast of Winnipeg.

'[The youth] and Edward may be responsible [for the fire], that's what they told me.'—Mary Anderson, the 11-year-old boy's foster mother

A fire on Jan. 2 destroyed the grandparents' home but they were located safe at a relative's house in the community. They gave no indication that anyone else might have been in the burned house, so it was believed the only damage from the fire was structural, RCMP said.

Police weren't notified until two days later that the boy was missing and Anderson found out later that same day. She said RCMP came to her on Monday, asking where Redhead and a 16-year-old youth might be.

"[The youth] and Edward may be responsible [for the fire], that's what they told me," she said.

It wasn't until Tuesday that human remains were discovered in the rubble of the home. They are suspected to belong to the boy, but that has yet to be confirmed, RCMP said.

Youth arrested by RCMP

On Thursday, RCMP announced the fire is being investigated as an arson-related homicide and that a 16-year-old boy from the community has been arrested. No charges have yet been laid.

A second set of remains was also found in the house on Tuesday but an autopsy has determined those to be from an animal. Shamattawa Chief Jeff Napoakesik said Thursday those remains could be from a caribou, which, he was told, was in the house when it burned.

The home where the remains were found had a gasoline heater, but it had run out fuel, and the homeowners — the boy's grandparents — locked up and left. There has been speculation the boy might have entered the empty home to search for gas to sniff.

David Harper, grand chief of Manitoba Keewatinowi Okimakanak, an organization representing most First Nations communities in northern Manitoba, said sniffing is big addiction problem in some northern communities.

Band officials on Friday said there aren't enough resources on the reserve to keep young people from getting themselves into trouble.

Despite that, it was the children in the community, not the adults, who sounded the alarm about Redhead missing and suggesting he might have died in the fire, officials said.

As a result, everyone in the community must take some degree of responsibility for failing Redhead, said Harper, who toured the area with media on Friday.

More children will die: provincial advocate

Gord Mackintosh, Manitoba's minister for child and family services, has promised a full investigation into the incident to determine whether Redhead was left unsupervised for hours or even days.

Manitoba Children's Advocate Billie Schibler said the investigation will look into a number of unanswered questions.

'There will still be children that will die and there will still be children … that the child welfare system will have to take account for.'—Billie Schibler, children's advocate

"How is it that a child in care is not where he is expected to be? Was the agency aware of the child not being in their intended placement at the time? How is it that a child was in a house that burned down and it took so long for people to realize this was a child in care?"

However, despite reviews and recommendations to the system, it's inevitable that some children will fall between the cracks in the system, Schibler said. "There will still be children that will die and there will still be children … that the child welfare system will have to take account for."

Child welfare officials have said there may have been a miscommunication between Redhead's foster home and his grandparents.

Anderson said Redhead had a habit of disappearing, and she would have to track him down and bring him back home.

"That's the kind of boy he was," she said.

Child welfare system review needed: Opposition

Manitoba's Opposition Progressive Conservative Party has called for an external review of the province's child welfare system.

Family services critic Bonnie Mitchelson said it's clear child welfare authorities lost track of who was supposed to be looking after Redhead.

Since the death of Phoenix Sinclair in 2005, about 20 children in care in the child welfare system have died.

Five-year-old Phoenix, a ward of Child and Family Services for most of her short life, was abused and killed in June 2005 on the Fisher River Cree Nation. No one outside her immediate family noticed she was missing until RCMP received a tip in March 2006.

Phoenix's mother, Samantha Kematch, and her common-law husband, Karl McKay, were convicted of first-degree murder in December 2008. They are not eligible for parole for 25 years.

'It was rushed ahead without …ensuring that people that working in the system had the training, and the ability, to put the safety of children first.'—Bonnie Mitchelson, family services critic

Kematch had regained custody of her daughter about a year before Phoenix died. A child welfare worker checked on the family in early 2005, but never saw Phoenix during the visit and no one ever followed up on the case.

Mitchelson also called for a full probe of the Awasis Child and Family Services agency. She said that when the government handed over the responsibility of aboriginal children to native child welfare agencies several years ago, it happened without the proper checks and balances being put into place.

The children have become the casualties of the inadequate and unaccountable system, she said.

"Devolution was a major change. It was rushed ahead without the proper training, without the proper protocols, without ensuring that people that working in the system had the training, and the ability, to put the safety of children first," Mitchelson said.