New documents released to the Truth and Reconciliation Commission (TRC) may shed some light on the number of children in British Columbia who died in residential schools.

The TRC was recently given over 4,000 documents, including death certificates for aboriginal children aged four to 19 who died between 1917-56 in British Columbia. It is unclear how many of them were residential school students.

The commission previously reported that at least 4,100 children died in 130 schools across the country, but that number could grow as more federal and provincial documents are analyzed.

A young girl prays at her bedside in a residential school. (CBC) "What we need to do is we need to take those names and cross reference them to the list of students who were in the various residential schools during that period of time to see if we can start matching names," said TRC chair Justice Murray Sinclair.

Sonny McHalsie is a researcher for the Sto:lo First Nation near Chilliwack. He hopes the list of names supplied by B.C.'s coroner and vital statistics department may eventually identify some of the children in unmarked graves located close to Coqualeetza residential school.

"We don't know anything about them, we don't know the names. It's important because families from different communities up north have called me and wanted to find out where their loved one was and we don't know where they are."

Approximately 150,000 children attended residential schools in Canada from the 1870s until the mid 1990s. The church-run and government-supported schools operated under a deliberate policy of "civilizing" aboriginal children.

The TRC's Missing Children Project has been working since 2008 to try to determine the number of children who went missing or died in residential schools across Canada.

"It is a time-consuming effort, but I think at the end of the day we will probably be able to do that for most of the children and ensure that our search of the records also will tell us whether the families were ever informed and what the families were told," said Sinclair.

Gary Williams's aunt attended the Kamloops Indian Residential School in British Columbia with her brother who died there, but the family was never told where he was buried.

"She's not too healthy now, but she was saying the last thing she wanted to do before she goes away is to find her brother," Williams said.

Boys in a classroom circa 1945 at St. Anne's Indian Residential School in Fort Albany, Ont. (Edmund Metatawabin collection/Algoma University) The majority of residential school students died of diseases like tuberculosis. Records also show children also died from malnutrition or accidents. Schools burned down, killing students and staff. Drownings or exposure were another cause. Some committed suicide. Justice Sinclair said mortality rates reached up to 60 per cent at some schools.

"There is pretty significant evidence that disease and illness were the major causes, but contributing factors would be the conditions within the schools. We do know for example there were many reports of assessments being done of the schools showing that one of the reasons why tuberculosis was such a major problem was because the schools were poorly ventilated and the children were malnourished and incapable of fighting off disease," Sinclair said

Last year, the federal government was ordered to release thousands of documents to the TRC from Libraries and Archives of Canada. Sinclair said researchers are still analyzing that information.

Students at Cecilia Jeffrey Indian Residential School. (CBC) Some of the documents released last year revealed the federal government conducted nutritional and medical experiments on thousands of children who attended residential schools.Those who survived were often subject to physical, emotional and sexual abuse.

In the 1990s, thousands of victims sued the churches that ran the schools and the Canadian government. The $1.9-billion settlement in 2007 prompted an apology from Prime Minister Stephen Harper followed by the creation of the commission in 2008.

So far, only Ontario and British Columbia have released provincial documents to the commission. Sinclair is hoping other provinces will follow suit. The commission's mandate was recently extended until June 2015.