Jacinda Miller, the victim of Monday evening’s shooting at the Brandywine YMCA, as pictured on her Facebook page. WEST BRANDYWINE — Authorities are trying to determine why a man gunned down his estranged girl friend and then shot himself to death Monday night at the Brandywine YMCA. Jacinda Miller, authorities, a fitness instructor at the YMCA, was shot by Dennis Cassel as she arrived at...