Preston was a Human female, a detective in San Francisco on Earth in the 21st century. During the Bell Riots of 2024 Preston lead negotiations with Michael Webb and Gabriel Bell on behalf of the police department and government authorities.
Preston sought to win the release of hostages being held in the Sanctuary Processing Center but Webb and Bell refused to release any hostages until their demands were met. Preston was unable to convince Governor Robert Chen to meet their demands, despite public opinion being swayed by the personal stories of residents that were broadcast over the Net, and ultimately had to order that the Processing Center be stormed. Several residents, including Webb, Biddle Coleridge, and presumably Bell, were killed in the action. (DS9: "Past Tense, Part II")