NORWAY HOUSE, Manitoba — Canada’s national police force said Friday that it is has started an investigation into two cases of babies who were allegedly switched at birth at a northern Manitoba hospital 41 years ago.

The Royal Canadian Mounted Police said it has an obligation to the families and the public to determine if the mix-ups were accidental or criminal.

Two men from Garden Hill First Nation first announced last year that DNA tests had proved they were switched at birth at the Norway House Indian Hospital in 1975.

Two other men from Norway House, born at the same hospital in the same year, came forward with the same story in August. DNA tests confirmed their story last month.

Tests show Leon Swanson is the biological son of the woman who raised David Tait Jr., while Tait is the son of the woman who raised Swanson.

Tests last November showed Luke Monias and Norman Barkman of nearby Garden Hill also went home from the hospital with the other’s family in 1975.

The two cases have raised the question of whether other babies could have been switched at the hospital.

Health Canada has said it would offer free DNA tests to anyone born at the hospital before 1980, after which the facility started fitting newborns with identification bands.

The police force said in a statement that its investigation will be separate from a review that Canada’s federal government announced earlier.