Local television and stage veteran Robert Prosky died yesterday after complications from heart surgery. He was to turn 78 on Saturday. Prosky was best known from his role as a police sergeant on Hill Street Blues, and had several film roles in movies such as Mrs. Doubtfire and Broadcast News. The actor recently appeared in a production of Arthur Miller’s The Price with his two sons at Theater J; that show was slated for an eight-week run in Vienna, Austria early next year. He resided in Capitol Hill.