(West Columbia, SC)  --  Authorities in South Carolina are searching for a soldier from Minnesota who has been missing for more than four days.  Twenty-six-year-old Army Sergeant Robert Larson of North Branch was last seen by his wife Saturday night.  The Calhoun County Sheriff's Office says they've been looking for Sergeant Larson and his black Jeep Wrangler in some off-road areas near his home.  Larson has been deployed to Iraq and Afghanistan and received a Purple Heart after suffering a traumatic brain injury.  A Facebook page has been set up to update family and friends on the search.