Mark Seibel, who oversees all international and national security coverage, joined the bureau from The Miami Herald, where he directed two Pulitzer Prize-winning reporting efforts, expanded the reach of the paper's International Edition, and oversaw the paper's independent review of ballots from the 2000 presidential election. He began his career at The Dallas Morning News in 1975 after graduation from Southern Methodist University. He covered Mexico and Central America as the Mexico City bureau chief of the Dallas Times Herald, and worked as an editor and reporter for the San Jose Mercury News and the Los Angeles Times before joining The Herald as foreign editor in 1984.

In 1987, The Herald international staff received the Pulitzer Prize for National Reporting for its coverage of the Iran-Contra affair. Seibel was appointed a Nieman Foundation Fellow at Harvard University during the 1991-92 academic year. He returned to The Herald afterward as director of international operations, where he directed both news and business operations of the paper's International Edition and edited a monthly publication devoted to the Cuban economy. He subsequently served as assistant managing editor for Page 1 and assistant managing editor for state and local news, where he directed the coverage of the Elian Gonzalez immigration saga that won the Pulitzer Prize for Breaking News in 2000. In 2001, he was named The Herald's managing editor for news.

He was assigned to Knight Ridder's Washington Bureau to coordinate reporters during both the Gulf War in 1991 and the March 2003 invasion of Iraq before moving to the bureau full-time later that year. He serves on the board of advisers to the Department of Journalism at SMU in Dallas.