In August 2005, Muir was inside the New Orleans Superdome as Hurricane Katrina hit and stayed in that battered city to cover the unfolding crisis. His reports for "World News" and "20/20" were the first to reveal the deteriorating conditions inside the Convention Center and Charity Hospital wading through chest-deep waters to get to the patients still inside the hospital. In October 2006, he was on the scene of the Amish schoolhouse shootings in Lancaster County, Pennsylvania. He also reported from West Virginia on the letters left behind by the coal miners during the Sago Coal Mine tragedy for "20/20."
Muir has contributed to several in-depth series on "World News " including "Going Home," "The Fight to Save the Middle Class," and the broadcast's "Key to Success" series, reporting on efforts to revitalize Yosemite National Park.
Shortly after joining ABC, Muir anchored ABC News' coverage of the ceremonies marking the 60th anniversary of D-Day, and in his first week on the air, he anchored several hours of the network's coverage of the Blackout of 2003.
Prior to joining ABC News, Muir distinguished himself as an award-winning anchor and correspondent for WCVB-TV, the ABC affiliate in Boston. He spent a month in the Middle East reporting on the war in Iraq, helping to earn the station the prestigious National Headliner Award. He spent several weeks in Florida reporting on the 2000 presidential election recount, and reported extensively on the sexual abuse scandal within the Boston Archdiocese.
While in Boston, Muir was part of the team that received the regional Edward R. Murrow Award for investigative reporting and Associated Press honors for his work tracing the path of the September 11th hijackers. His anchoring and reporting of breaking news in Boston earned top honors from the Associated Press.
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.