Usually, no investigations are done. (AICPA recommends setting a process and following it.) If a client or friend recommends someone that is nearly always sufficient for me.  But this engagement is telling my gut to walk slowly.  

Thanks for the advice Ironman

An interesting tidbit to share:

1. Cannabis lab, likely sprung up here in CA in 2017 when state regulatory environment was lacking and many new entrants came in - some with low ethical and business standards.

2.  A small shareholder "unlawfully" dissolved the corporation with the Secretary of State. He wants to reinstate it. I'll learn more later.