(Duluth, MN)  —  A fatal police-involved shooting following a February standoff in Duluth has been ruled justified.  Yesterday, St. Louis County Attorney Mark Rubin said officers used necessary force in shooting David Conwell.  Conwell barricaded himself in a local house for about 19 hours and fatally shot a K-9 sent into the residence by police.  Police say Conwell then fired off shots three more times, resulting in four officers and two deputies returning fire.  He died from bullets shot by the deputies involved.