Upon graduation from Northwestern State College, where he earned his bachelor’s degree in accounting, Marcus moved to Monroe. In the summer of 1963, he began his career in public accounting with a local CPA firm.  After working for that firm for seven years, he opened his practice in 1970. After about 10 years, he partnered with fellow Northwestern State alumnus John Robinson to form Marcus, Robinson and Hassell which has offices in Monroe and Winnsboro.

Marcus has been involved in a number of successful business ventures throughout Louisiana and Arkansas which include healthcare companies, restaurants, commercial and residential development and management.

Marcus has supported NSU for decades and has served on numerous boards and committees that enhance the university, including the NSU Foundation Board, The Mary R. Gallaspy Trust No. 2 Board and the College of Business and Technology Advisory Board. He has also been honored as a member of the NSU College of Business Hall of Fame.

Marcus is active in state and national professional organizations, including the American Institute of Certified Public Accountants and the Louisiana Society of Certified Public Accountants. In 2019, he received the certificate of recognition for 50-years loyal membership in the Louisiana Society of Certified Public Accountants.

He has supported and donated to countless athletic and academic programs at NSU over the years, including establishing a faculty endowed professorship, and joined NSU alumni Bill Tilley, Bill Stokes and Joe Singletary in establishing a four-year endowed scholarship through the NSU Foundation.