He served ten years in the Criminal Division of the King County Prosecutor’s Office, including five years as the chief of the Juvenile Court Section. He was a partner in the former Mckay and Gaitan law firm for four years, focusing on civil litigation. In 1989 Mark was elected to the first of three terms as Seattle City Attorney, leading an office of 70 attorneys and 100 staff. Among other things, he formed the first specialized domestic violence prosecution unit in Washington, teaming specially trained prosecutors and victim advocates.