He served on the Town of La Plata's Business District Commission and the Charles County Community College Board of Trustees from 1993 to 1995.

[4] In April 2004, Mitchell announced that he would not seek re-election in 2006, saying that he wanted to spend more time working at his business and with local charities.

[4] He resigned from office early after Governor Bob Ehrlich appointed him as principal deputy secretary of the Maryland Department of Health in September 2004.

[5] On December 23, 2014, Maryland Governor-elect Larry Hogan appointed Mitchell to be his Secretary for the Department of Health and Mental Hygiene.

[10][11] On December 15, 2016, amid pressure from state legislators to more promptly care for criminal defendants awaiting psychological evaluations, Mitchell resigned as Secretary of Health effective immediately to "pursue opportunities in the private sector".