Who is Ed Best from One True Thing and what is their importance?

Ed Best is the district attorney in Langhorne. He is the lawyer who prosecutes Ellen's murder trial and many, Ellen included, believe that he only pressed charges against Ellen to create a media frenzy during the time of his re-election campaign. Now, with Ellen's story in the papers, he is on the front page nearly every day even though he is often described in the text as a dim-witted attorney.