WINNIPEG -- The Assembly of First Nations is calling for an independent probe of how police handled the disappearance of a teen whose body was eventually pulled from the Red River wrapped in a bag.

Police in Winnipeg are conducting an internal investigation after discovering two officers came across Tina Fontaine during a traffic stop in August -- a week after she had been reported missing -- but did not take her into custody.

The 15-year-old was last seen the following day. Fontaine's body was found more than a week later.

Police say the two officers have been put on administrative duties while the investigation is ongoing. But Cameron Alexis, Alberta regional chief with the Assembly of First Nations, says an internal review isn't enough and the province should bring in independent investigators.

"It is unfathomable that police officers would not take into their care a teenage girl who is reported missing," Alexis, who is also a retired RCMP member, said Tuesday. "It appears to be a systemic failure from top to bottom ... This is an example of what's going on across the country."

An independent analysis is needed to determine why Fontaine was not taken into custody by police and the federal government should call a national inquiry into almost 1,200 missing and murdered aboriginal women, Alexis suggested.

"Aboriginal leaders are getting extremely frustrated," he said. "You've got to look at it very carefully to ensure that our people are not being devalued."

Manitoba Attorney General Andrew Swan was not available for comment, but spokeswoman Sally Housser said the government agrees more must be done to "address the pressing issue of murdered and missing aboriginal women." She stopped short of agreeing to call an independent investigation.

"We appreciate the concerns expressed by the Assembly of First Nations and will work with First Nations leaders and the Winnipeg police service to ensure that the investigation gets to the root of how a tragedy like this can occur," she said in a statement.

The province's chief medical examiner has not decided whether to call an inquest while the case is still under police investigation.

Fontaine's body was found on Aug. 17 after she ran away from her Winnipeg foster home. She had been there less than a month. Police are treating the case as a homicide but have yet to make any arrests.

The teen's death touched a nerve and renewed calls for a national inquiry. The Conservative government has rebuffed the requests but agreed to participate in a roundtable on the issue.

As police search for Fontaine's killer, details have begun to emerge about her final days.

Her relatives say they have been told that a few hours after police came across Fontaine, the teen was found passed out in a downtown alley. Paramedics took her to a nearby hospital where she stayed for several hours before social workers picked her up. She managed to run away again and disappeared for good the following day.

Along with the internal police investigation, Child and Family Services is doing its own investigation, but the results aren't likely to be made public.

"I am offended and hurt that we have lost another child to a system that is failing our people," Alexis said. "In a case like this, it should be an outside agency conducting a full and thorough investigation from an outside view."

But Grand Chief Derek Nepinak of the Assembly of Manitoba Chiefs said he's met with Winnipeg police Chief Devon Clunis about the investigation into Fontaine's death and says the focus should be on finding her killer.

"I do believe that the Winnipeg Police Service are dedicated to finding that out," said Nepinak, adding they need time to conduct their internal investigation. "I wait for the outcome of that investigation and if we deem that it's been an inappropriate process, we will hold the Winnipeg Police Service and the city of Winnipeg to account.

"First and foremost, we need to find out who did this to this young girl."