district attorney 
(abbreviation DA)
noun
(In the US) a public official who acts as prosecutor for the state in a particular district.The report examines the corruption of some of the union officials who have not been prosecuted by the district attorney's office....
- Biely resigned from the district attorney's office and officially withdrew as a candidate, but could not get his name off the ballot.
- Only if a manufacturer refused to comply could the bureau turn the case over to a district attorney for prosecution.