35 years ago Robert M. Morgenthau assumed the leadership of a district attorney’s office that was almost broke in a city that was so crime-ridden that, according to Mr. Morgenthau, wives of executives transferred to Manhattan often refused to make the move.

On Thursday at midnight, Mr. Morgenthau, 90, will retire as the Manhattan district attorney, leaving behind for Cyrus R. Vance Jr., a former assistant, an agency that he made the template for the modern urban prosecutor’s office.