Democratic Party politician who served as Mayor of Rockville, Maryland from 1987 until 1993. He also held office for over a decade as Executive of Montgomery County, Maryland.
He studied political science and psychology at New York City's Columbia University and subsequently worked in the criminal justice field in Montgomery County, Maryland.
He briefly sought his party's nomination in the 2006 Maryland gubernatorial race; however, he ended his bid as a result of a battle with depression.
He married Barbara Duncan in 1980; they later became parents to five children.
Television actor Jay O. Sanders played Duncan in a 2003 television movie based on the Washington, D.C.-area sniper attacks of late 2002.