Shannon was special counsel for the Richmond Multi-Jurisdictional Grand Jury from 2004 to 2008. This position provided an opportunity to gain valuable experience working with additional agencies, such as the Virginia State Police, the Alcohol Beverage Control Board, and the Virginia Department of Taxation. After three years in private practice, Shannon was elected Commonwealth’s Attorney for Henrico County in 2011, the first woman to hold that position in the County’s history. She was re-elected in 2015 and again in 2019, this time winning the entire County.