A district attorney (D.A.) (or in New Jersey County Prosecutor and in Baltimore and Chicago State's Attorney (S.A.)) is the title of the local public official who represents the government in the prosecution of alleged criminals. It is typically an elected position, as in New York City, but this can vary from one jurisdiction to another. The D.A. is the highest officeholder in the jurisdiction's legal department and supervises a staff of executive assistant district attorney and assistant district attorneys.
In current canon, an unnamed character is now District Attorney.