A branch of Canada’s federal police force says it has spent the last decade conducting a “large-scale investigation” into allegations of sexual abuse at a former residential school. On Tuesday, the Manitoba Royal Canadian Mounted Police said it launched a criminal investigation in 2011, investigating claims that students were assaulted during their time at the Fort Alexander residential school. The rare disclosure of an ongoing investigation was prompted by questions from the Winnipeg Free Press newspaper. “Due to the many people affected by this investigation as well as the larger social implications, it was determined to be in the public interest to provide as much information on the ongoing investigation as we can,” the RCMP said in its news release. At least 150,000 Indigenous children were forced to attend residential schools across the country, which were funded by the federal government and run by churches as part of the campaign to strip the youth of their cultural identity. The Fort Alexander residential school, 125km (78 miles) north-east of Winnipeg, opened in 1905. Children often tried to run away from the institution, according to the Indian Residential School History and Dialogue Centre. In 1928, two boys drowned while trying to escape by boat. It was closed by the federal government in 1970. Elders have long spoken about abuse within the institution, including testifying at the country’s truth and reconciliation commission. More than 80 RCMP officers have been involved in the investigation so far, which has involved speaking to more than 700 people across North America. Investigators travelled to Ottawa to scour archival records from the school, as well as the province of Manitoba’s records. They also canvassed residents in the area where the school was located, on the grounds of the Sagkeeng First Nation. Police obtained 75 witness and victim statements. Grand chiefs of the Assembly of Manitoba Chiefs and the Southern Chiefs’ Organization have worked closely with police on the investigation, as have the chief and council of the Sagkeeng First Nation. In addition to testimony of abuse, survivors have long said children went missing or died while attending the school. Last week, teams searched the grounds of Sagkeeng First Nation using a drone and ground-penetrating radar technology to look for human remains. To date, more than 1,300 unmarked graves have been discovered on the grounds of former schools, prompting a national reckoning over Canada’s colonial past.