Mark Lee Greenblatt served as Inspector General for the U.S. Department of the Interior from 2019 to 2025, where he led nearly 300 investigators, auditors, and attorneys responsible for oversight of more than 70,000 agency employees. His work bolstered the integrity of the agency’s programs, rooting out waste, fraud, and abuse in the agency’s $10 billion in grants and contracts and $12 billion in natural resource royalties.

Mark led high-profile inquiries and investigations including the clearing of Lafayette Park during the Black Lives Matter protests in 2020, the events on the National Mall on January 6, 2021, the 2017 fatal shooting of an unarmed driver on the George Washington Parkway, and the 2024 pro-Hamas protests at Union Station.

Mark was elected in 2022 by the 74 Inspectors General to serve as Chairman of the Council of the Inspectors General, leading the Inspector General community’s 14,000 employees to combat fraud, waste, and mismanagement. He served as the IG community’s primary liaison with the White House, Congress, media, and the American public.

Mark previously served in leadership roles at the U.S. Department of Commerce Office of Inspector General and the U.S. Senate Permanent Subcommittee on Investigations. He served as an investigative counsel at the U.S. Department of Justice. He clerked for U.S. District Judge Anita B. Brody and was a litigator at international law firms. He also served as vice chair and commissioner of the Montgomery County, Maryland Ethics Commission, and he was an adjunct professor at the American University School of Law.

Mark is the author of Valor, untold stories of 21st century American soldiers, sailors, and Marines who faced gut-wrenching decisions to overcome enormous odds. He is a frequent speaker at events, regularly appears in the news media, and publishes articles, book reviews, and op-eds in top publications.

Mark graduated from Columbia University School of Law, where he was a Harlan Fiske Stone scholar. He earned his undergraduate degree from Duke University.