Gillies, a Chicago native, started his FBI career in 1983 as a financial analyst. Two years later, he became a special agent and worked in the Albany Division investigating white collar and public corruption cases, the FBI said.
In 1989, he went off to New York and in 1993 was transferred to the San Diego Division where he where he investigated bank failures and also judicial corruption, which resulted in the conviction of three California Superior Court judges.
He eventually went to the Honolulu Division in 1996 and six years later was promoted to unit chief of the Financial Institution Fraud (FIF) unit of the Criminal Investigative Division at FBI headquarters, the FBI said.
In 2004, he became assistant special agent in charge in Detroit and in 2006 he returned to headquarters as the section chief of the violent crimes section of the Criminal Investigative Division. the FBI said. Three years later he was named special agent in charge of the St. Louis Division.