(CNN)The first forensic evidence that unmarked graves in their hundreds were located at the former Kamloops Indian Residential School was a juvenile rib bone and tooth found beneath the apple orchard.
Thousands of children from Canadian schools for indigenous communities may be buried in unmarked graves, officials say
But survivors of the school say they didn't need forensic proof to know that hundreds of children went missing in Kamloops. And this week, new scientific evidence supported what indigenous elders in the Canadian province of British Columbia call the "Knowing."
In an emotional presentation by the Tk'emlúps te Secwépemc First Nation on Thursday, officials investigating the unmarked graves warned that more were likely to be found in the coming months.
"After all, this investigation has barely scratched the surface, covering just under two acres of the total 160-acre residential school site," said Sarah Beaulieu, a specialist in ground-penetrating radar who has been leading the forensic investigation.
As many as 200 graves have been found, according to preliminary results, down from an initial estimate in May of 215, but Beaulieu said that number could be revised higher with more forensic investigation and excavation.
"This fact, this 'knowing' has been recognized by indigenous communities for generations," Beaulieu said. "All residential school landscapes are likely to contain burials of missing children and remote sensing such as GPR merely provide some spatial specificity to this truth."
The evidence presented Thursday underscored the magnitude of the abuse and neglect of indigenous children, not just in British Columbia, but in dozens of residential school sites across Canada. Similar forensic investigations are underway at dozens of sites.
"We're talking clearly about thousands and thousands of missing children," said Lisa Hodgetts, president of the Canadian Archaeological Association.
Kamloops' survivors bore witness to the findings during the presentation and painted a bleak picture of what children as young as 5 were subjected at these schools, a term many survivors say they use with scorn as they say they were not educated, but instead neglected and abused sexually, physically and emotionally.
Evelyn Camille, a survivor of Kamloops, spoke about the abuse and neglect, about how many died trying to run away from the school, either drowning in a nearby river or freezing to death after they tried to escape in winter.
"We had tried to mention over and over and over, there are many children missing who did not reach home," Camille said.
The school, initially known as the Kamloops Industrial School, was opened in 1890 and remained in operation until 1978. It was opened and run by the Catholic Church until the federal government took it over in the late 1960s.
"I think it's unfortunate, as Dr. Beaulieu already noted, that it took the science to wake the world up to the truth that survivors and communities have known for years," Hodgetts said during the presentation.
Rosanne Casimir, chief of the Tk'emlúps te Secwépemc First Nation where the school is located, said both the federal government and the Roman Catholic Church should fully disclose all records of those who attended the schools.
"We are loath to put the responsibility of identifying those lost on the survivors of Kamloops Indian Residential School, who have been traumatized and re-traumatized already," Casimir said, calling on Prime Minister Justin Trudeau and the Canadian government to share the attendance records.
It would be "a first step in assisting Tk'emlúps te Secwépemc in fulfilling their obligations regarding those lost without acknowledgment and as steps towards reconciliation," Casimir said.
The Canadian government has said that it would fund more investigations into unmarked graves in indigenous communities across the country, but it has also faced criticism for not doing so sooner, as outlined by the Truth and Reconciliation Commission in its 2015 report.
Trudeau has said since the initial discovery in Kamloops in late May that his government will cooperate and provide funding for investigations.
"There will be more funding as necessary to continue to allow communities to grieve, to heal, and to get answers," Trudeau said during a news conference in Montreal on Thursday. "And at the same time we have also committed over many years and we will continue to recommit to sharing any and all records that the federal government has in helping to identify these graves," he said.
Indigenous leaders have said in recent weeks that what happened in the schools were crimes and that they should be investigated as such.
Survivors at the presentation talked about how traumatized they have been in recent weeks, reliving their past abuse and mourning for those children who lost their lives.
"I can remember a boy named Riley, cowering under one of the supervisors in the bathroom and it wasn't too long after that he supposedly hung himself," said Bruce Allen, a residential school survivor, in an interview with CNN from at the Kamloops site.
Allen said there is no way of knowing if that boy, who he assumes was about 12 years old, committed suicide after being "tormented," or if a crime was committed.
He says in recent weeks he has watched hundreds of people, including many non-indigenous Canadians, come to pay their respects at a memorial on the school grounds and he says many have now come to know the truth about Canada.
Allen works as a counselor with a crisis line for survivors and he says some who have reached out to him since the initial discovery of unmarked graves, have never spoken of the abuse they have suffered or the abuse they may have witnessed.