By Darryl Greer Canadian Press MISSION, BRITISH COLUMBIA- An investigation into unmarked graves and missing children by British Columbia’s Sto:lo Nation has revealed at least 158 deaths, most of them at a hospital. But representatives from the Sto:lo Nation Chiefs’ Council and Sto:l? Research and Resource Management Centre said Thursday that their work has only just begun, and is being hampered by lack of access to information from the federal government and religious institutions that were involved in the schools. As part of the nation’s “Taking Care of Our Children” project, researchers provided Sto:lo members and the media with an update Thursday on archival research, field work involving ground-penetrating radar, and genealogical research into historical sites of three residential schools, cemeteries and a First Nation hospital. Researchers with the nation…