Lou is a Certified Public Accountant (CPA) in Michigan and Illinois as well as a Registered Professional Engineer (PE) in Michigan. He holds certificates in internal auditing (CIA), information systems (CCP), information systems auditing (CISA), fraud examination (CFE), management accounting (CMA), and financial management (CFM).

Since 1969, Dr. Petro has taught auditing, systems, accounting, and finance courses at:
- Hillsdale College
- Michigan State University
- Lawrence Technological University (LTU)
- Oakland Community College
- Oakland University
- University of Detroit-Mercy
- University of Michigan
- Walsh College
- William Tyndale College
- Wayne State University
- The University of Windsor.

He was the Dean of the LTU School of Management from 1979 through 1989.

From 1971 through 1979, Dr. Petro held consulting and auditing positions at the CPA firms of Ernst and Young, Plante and Moran, and Grant Thornton. He was a Management Advisory Services (MAS) Manager at Grant Thornton in Chicago immediately prior to becoming the Dean at LTU.

Prior to his auditing and consulting career, Lou was a manufacturing engineer at the Chevrolet Division of General Motors (GM) and the GM Manufacturing Development Staff.

Dr. Petro remains active in CPE for CPA’s, CIA’s, and CMA’s. He regularly conducts classes and seminars for the Michigan Association of CPA’s, the Oakland University CPE Program for CPA’s, the Institute of Internal Auditors, and the Institute of Management Accountants. In addition, Lou is a question writer for the US CMA examination.