Muir joined WCVB-TV after spending five years as an anchor and reporter at WTVH-TV in his hometown of Syracuse, New York. While in Syracuse, he filed reports from Jerusalem, Tel Aviv and Gaza City following the assassination of Israeli Prime Minister Yitzhak Rabin, earning top honors from the Radio-Television News Directors' Association. He also anchored the station's coverage of President Clinton's impeachment trial from Capitol Hill. The Associated Press honored him for Best Enterprise Reporting and Best Television Interview. The Syracuse Press Club recognized him as anchor of the Best Local Newscast, and he was voted one of Syracuse's Best News Anchors by the readers of "The Syracuse New Times."
A magna cum laude graduate of Ithaca College, Muir attended the Institute on Political Journalism at Georgetown University and studied at the University of Salamanca in Spain.