He previously served as an assistant United States attorney in the Eastern District of Virginia for approximately nine years, where he prosecuted organized crime, human trafficking, complex violent crime, and financial fraud offenses. He also served as leader on multiple, regional task forces as well as counselor to the U.S. attorney. During his time as an assistant United States attorney, he was detailed to the Senate Judiciary Committee where he served as a criminal counsel to Chairman Charles Grassley.
Prior to becoming a U.S. attorney, Terwilliger served as an associate deputy attorney general in the Office of the Deputy Attorney General with responsibility for overseeing aspects of the department's Criminal Division and management of staff within the Office of Deputy Attorney General.[5]
Senators Tim Kaine and Mark Warner recommended Terwilliger to serve permanently as United States attorney.[7] On July 13, 2018, President Donald Trump announced his intent to nominate Terwilliger to be the U.S. attorney for the Eastern District of Virginia.[5] On July 17, 2018, his nomination was sent to the United States Senate.[8] On August 23, 2018, his nomination was reported out of committee by a voice vote.[9] On August 28, 2018, the United States Senate confirmed his nomination by a voice vote.[10][11] On January 5, 2021, The United States Attorney General's Office released a statement confirming that Terwilliger would resign as the U.S. attorney for the Eastern District of Virginia effective January 15, 2021.[12][13]