"6,000 children died and buried in unknown graves"

The commission that has spent five years examining one of the darkest chapters in Canada's history is winding up its work with a key question left unanswered - exactly how many aboriginal children died in residential schools?

Justice Murray Sinclair, who heads the Truth and Reconciliation Commission, says the federal government stopped recording the deaths around 1920, after the chief medical officer at Indian Affairs suggested children were dying at an alarming rate.

"He was fired," Sinclair says.

"The government stopped recording deaths of children in residential schools, we think, probably because the rates were so high.

Sinclair has guessed up to 6,000 children may have died at the schools but it's impossible to say with certainty.

"We think this is a situation that needs further study," he said.

The commission didn't originally intend to examine how many children never came home, but it quickly emerged as an issue, Sinclair says.

Schools were often crowded, poorly ventilated and unsanitary. Children died from smallpox, measles, influenza and tuberculosis. Some were buried in unmarked graves in school cemeteries, while others were listed as "missing" or "discharged." In some cases, parents never found out what happened.

Some provinces handed over death certificates to the commission, but Sinclair says the work is far from over.

The commission found deaths unrecorded, names unrecorded, genders unrecorded and burials in unmarked graves in often forgotten child graveyards.

"We have recommendations around that in the report. We're going to tell you there are lots of records out there that are missing."

The medical experiments conducted on children, as well as forced military training, should also be properly studied.