A native of Arlington, Massachusetts, Sullivan received his bachelor's degree from Saint Anselm College in Manchester, New Hampshire in 1977. His career spans a total of 29 years in federal law enforcement, 24 of which have been in the Secret Service. He worked as a special agent in the Office of the Inspector General for the Department of Housing and Urban Development (HUD) for three years before joining the Secret Service as a special agent assigned to the Detroit Field Office in 1983. In 1990 Sullivan was transferred to the Fraud Division in Washington, D.C., where he coordinated and monitored multi-jurisdictional criminal investigations involving credit card fraud, bank fraud, and similar criminal activity. In 1991 he received his first assignment to the Presidential Protective Division, where he worked for four years. He entered the agency’s supervisory ranks in 1996 when he was promoted to Assistant Special Agent in Charge of the Office of Protective Operations. He returned to the field the following year as the Resident Agent in Charge of the Columbus Resident Office, overseeing all Secret Service activities in Central Ohio. Thereafter he was promoted and transferred back to Washington, D.C. as Deputy Special Agent in Charge of the Counterfeit Division, In July of 1999, he returned to the Presidential Protective Division, this time as an Assistant Special Agent in Charge. In 2000, Sullivan was promoted into the federal Senior Executive Service as a Deputy Assistant Director in the Office of Protective Operations. In 2002, he was reassigned to the position of Deputy Special Agent in Charge of the Vice Presidential Protective Division. A year later, he was reassigned to the position of Deputy Assistant Director, Office of Human Resources and Training. He was the Assistant Director for the Office of Protective Operations before being named Deputy Director, and then Director in 2006.