An investigation commissioned by U.S. Interior Secretary Deb Haaland found graves at 65 of the more than 400 U.S. boarding schools where Native American children were forced to assimilate into white, …An investigation commissioned by U.S. Interior Secretary Deb Haaland found graves at 65 of the more than 400 U.S. boarding schools where Native American children were forced to assimilate into white, …