GRAPHIC WARNING: This article contains details readers may find disturbing.

An organization investigating unmarked graves near a residential school in eastern Alberta says it has uncovered physical and documented evidence of a genocide.

The Acimowin Opaspiw Society (AOS) released details of its preliminary report Tuesday into missing children and unmarked burials at Blue Quills Residential School.

The investigations theory regarding the missing children of the Saddle Lake site, is that they are buried in undocumented mass graves, the report states.

One of the undocumented mass graves was located by accidental excavation, in 2004, at Sacred Heart cemetery. The mass graves will require a second excavation, and repatriation of remains followed by the identification by the coroner once DNA is collected from living descendants.

The report includes allegations that a disciplinarian who worked there from 1935 to 1942 was seen killing children.

The investigation has received disclosures from intergenerational survivors, whose parents witnessed homicides at the Saint Paul site, the report states.

That staff member is accused of pushing boys down the stairs, killing them.

[He] would then threaten to kill the boys that witnessed if they said anything, it says.

The report states the accused died in 1968.

Leah Redcrow, executive director of AOS, also believes that many of the children at the school died after they were forced to drink unpasteurized milk that was contaminated with bovine tuberculosis.

How I know its deliberate is because the school administrators werent dying, the children were. And the school administrators didnt eat the same food as the children, Redcrow told reporters.

A lot of what this is, is getting spiritual justice for our family members who are missing. I myself didnt know that my grandfather had 10 siblings die in this school.

Genealogical work is being done to determine how many children disappeared, she said.

Last May, the group held a press conference to announce that it was actively researching and investigating the deaths of at least 200 residential school children who never came home.

At the time, a residential school survivor and researcher with AOS said he found documents for 215 students who died between the ages of 6-11, but whose remains are still unaccounted for.

The amount of missing children is extensive...The institution was strife with violence, illness, starvation, abuse and death, said Eric Large.

A councillor in the community also spoke about finding body parts in unmarked graves at the Sacred Heart Cemetery in Saddle Lake, and the report states skeletal remains including those of young children were found in the area.

If you are a former residential school student in distress, or have been affected by the residential school system and need help, you can contact the 24-hour Indian Residential Schools Crisis Line at 1-866-925-4419, or the Indian Residential School Survivors Society toll-free line at 1-800-721-0066.