The Canadian Press The RCMP is asking for the public’s help after a fire in Alberta destroyed a trailer being used for residential school investigative work. Police say an ATCO trailer burned down in May at the Sacred Heart Cemetery, near the former residential school of the same name in Saddle Lake, Alta., northeast of Edmonton. Mounties say they don’t have any suspects but believe people in the community “possess vital information” that could help solve the case. They say the trailer belonged to the Acimowin Opaspiw Society. The society says on its website that it represents survivors of the Blue Quills Residential School, known at one point as Sacred Heart, and their descendants. The National Centre for Truth and Reconciliation says the school was under First Nations control when…