AN AUTOPSY today should reveal how 11-year-old Celina Cass was killed. The New Hampshire girl's body was found Monday morning at a damn in the Connecticut River after a week-long search around her hometown of West Stewartstown--about a mile from the Canadian border. Cops believe she was murdered and a full manhunt in now underway for her killer. Last night a candlelight vigil was held for the quiet, popular girl as the crowd sang "Amazing Grace." Her best friend collapsed in tears.Her dad Adam Laro said of Celina: "Very sweet, very outgoing, very generous










