About the Chief Mark Sisson has served as Chief of the Christiansburg Police Department since 2007. Chief Sisson began his career in law enforcement in 1995, when he joined the Christiansburg Police Department. He has served as a patrol officer, drug task force investigator, investigations sergeant, patrol lieutenant, and investigations lieutenant. He holds a bachelor’s degree in organizational management and leadership and an associate’s degree in criminal justice. Chief Sisson also served six years in the Marine Corps.