ALEXANDRIA, La. — Hospital officials called it an accident when a 70-year-old psychiatric patient was fatally injured in an altercation with a nursing assistant at a Department of Veterans Affairs medical center in central Louisiana three years ago.But the case became fodder for the VA's congressional critics after local prosecutors charged the employee, 54-year-old Fredrick Kevin Harris, with manslaughter in the death of Air Force veteran Charles Lee Johnson.Johnson died a year before a national scandal erupted over chronic delays for veterans seeking medical care.