California Corporate Changes

We are a business in California and had just completed the Incorporation process for our business when one of the main partners/officer decided to not only abruptly leave the firm (for personal reasons) but also removed a large sum of money from the business/corporate account that he was involved with when the company first began as a partnership. At this point one would think that he was satisfied with his exit but now we are hearing through businesses and people we deal with that this person going from business to business trying to collect money on behalf of the company and also is making some very derogatory statements concerning the company and the president of the corp.
My question is "What can we do to not only protect ourselves from any legal backlash but also what legal rights, if any, do we have to possibly pursue some sort of legal recourse against this person?"