Kisha Supernant felt a painful weight in her chest as she waited for the telltale beep of her radar equipment.

Disturbances deep in the earth — captured by the ground-penetrating radar — outline the shape of what appears to be a small, crudely dug grave.

The Edmonton-based anthropologist is among a small team of researchers using radio-wave technology to locate the unmarked graves of children who died at a residential school in east-central Saskatchewan.

So far, researchers have identified 10 to 15 potential burial sites. They will return this summer to search for more.

There was a darkness about the place, Supernant said.

"The area where we found the most anomalies, the three of us who were doing the survey, none of us were surprised that was the area, because you could kind of feel it when you were there," Supernant said.

"There was a heaviness."

'The work is difficult'

Supernant and her University of Alberta graduate student, Liam Wadsworth, joined Terence Clark of the University of Saskatchewan's department of archaeology and anthropology this summer in surveying the fields surrounding the Muskowekwan Residential School, which sits on a reserve by the same name.

"The work is difficult and emotionally challenging in some ways, but it is among the most important and meaningful work I ever have had the chance to do," Supernant said in an interview with CBC Radio's Edmonton AM.

"It really feels important."

Hundreds of students passed through the now-abandoned school before it closed in 1997. Some vanished without a trace.

At least 35 children were unaccounted for in the school records, Supernant said. It had long been thought the fields surrounding the derelict brick building held the unmarked graves of children.

In the early 1990s, when the building was still operating as a school, waterline construction unearthed human remains.

The National Centre for Truth and Reconciliation, in collaboration with the Muskowekwan First Nation, has asked researchers to identify the rest of the unmarked burial sites.

The centre has said the children need to be found. Supernant was proud to answer that call to action.

"A lot of the work that I have done throughout my career has been driven by community needs and requests," she said. "And being Métis myself, I am very committed to doing work that supports the goals of Indigenous communities."

Archeologists Kisha Supernant, right, and Terence Clark use ground-penetrating radar to search for unmarked graves. (Kisha Supernant)

Supernant's team relied on the memories of community members to find the places where the missing children may have been laid to rest. The radar detected underground disturbances in three different sites identified by survivors and other community elders.

The technology is non-invasive, allowing the community to decide what to do with the remains without disturbing them.

"They took us out to areas where they had either heard or seen things that might indicate unmarked graves, and then we set up grids over those areas," Supernant said.

"And once we've laid that [grid] over the ground, we take the ground-penetrating radar equipment and we run it back and forth across that entire grid, and the radar gives us a signal when something is unusual underneath the surface of the ground."

Some disturbances in the earth were more distinct than others.

"These are anomalies," she said. "We cannot, with 100 per cent certainty, say that they are for sure burials and graves. But they're in areas where people had heard of there being these types of burials, and we can confidently say between 10 and 15 of those types of anomalies were found.

"One, we're pretty sure, was a coffin burial, which was pretty unexpected. It had a pretty distinct signature."

There were a lot of ways in which these children could have disappeared. - Kisha Supernant

Burying students in unmarked graves was not uncommon in Canada's state-sanctioned, church-run residential school system.

Child mortality rates were disproportionately high and there was an institutional indifference to the dead. The Truth and Reconciliation Commission estimates that 3,200 students died while attending residential schools from 1867 to 2000.

Children forcibly separated from their families were often poorly nourished, strictly disciplined and subject to neglect and abuse.

"There were a lot of ways in which these children could have disappeared," Supernant said. "It could have been illness, there was a lot of physical abuse that could have gone too far.

"There were runaways. And if bodies were recovered, they may not have been buried in official cemeteries."

A view from the second-floor stairwell of the school shows a stand of trees near what is said to be an unmarked cemetery. (Penny Smoke/CBC)

The bodies of children were rarely sent back to their home community. The dead were usually buried in cemeteries close to the schools or nearby mission, sites that were often forgotten or fell into disrepair when the institutions eventually closed.

Record-keeping practices were poor. The names of the dead were often left off the record. Some families were never told when or how their children died.

The Muskowekwan First Nation community, which is about 150 kilometres northeast of Regina, has been trying to turn the deteriorating school building into a museum, and wants to mark the graves and honour their dead.

"They plan to commemorate the burials in some way and use it as a way to tell the history of residential schools," Supernant said. "They have one of the few residential schools in Western Canada that is still standing.

"They want to tell the story so it doesn't get forgotten. This is part of the telling."