Mark Hojnacke is the Director of the Office of Security and Threat Management, within the Office of Environment, Health, Safety and Security (EHSS), responsible for the development of Departmental security directives, implementation of certain elements of the National Industrial Security Program, and the Technical Security Program at the Department. He possesses 40 years of physical security experience as both a contractor and a federal employee, encompassing expertise in protective force operations, physical security systems, performance assurance, security risk management, and security policy. His contributions in these areas have been recognized throughout his career, including leading the EHSS team during the 2024 International Atomic Energy Agency's International Physical Protection Service visit – the first such visit in DOE history.
He began his DOE career in 1987 as a Security Inspector at the Nevada Test Site. During his tenure in Nevada, he advanced through various security positions of increasing responsibility. In 2010, he transitioned to a contractor support role within the Office of Security (predecessor to the Office of Security and Threat Management), subsequently becoming a federal employee in 2014. While he was in the Office of Security, the Department began revising its security policies to adopt a more risk-informed approach; an approach he continues to champion. He is a veteran of the United States Air Force, where he served as a Security Police Officer from November 1981 to November 1985.