David Walker is the Comptroller of the United States. He began his fifteen year career in 1998 when he was appointed by President Clinton in 1998.
Before becoming comptroller, Walker worked at Arthur Andersen LLP, where he was a partner and global managing director. He was also a member of the board of Arthur Andersen Financial Advisors and a Public Trustee for Social Security and Medicare from 1990 to 1995. Before joining Arthur Andersen, Walker was Assistant Secretary of Labor for Pension and Welfare Benefit Programs from 1987 to 1989 and in 1985, was Acting Executive Director of the Pension Benefit Guaranty Corporation. His earlier technical, professional, and business experience was with Price Waterhouse, Coopers & Lybrand and Source Services Corporation.
Source - http://faculty.msb.edu/walkerd/