CACI would not comment on whether it planned to replace Regester, but did confirm her departure.
It hired Regester two years ago to work with Tracy Weir, business director, to lead the expansion of its direct marketing business in the database hosting and CRM analytics sectors.
She joined CACI in April 2005 from Arc Worldwide, where she was data strategy director.
Prior to her time at Arc, Regester ran her own CRM consultancy, advising clients including Norwich Union and The Economist on data, technology and management issues and helping them to establish CRM programmes.
She began her career with database marketing bureau Printronic International and subsequently become managing director of Information for Marketing, which was later acquired by Harte Hanks.