Forensic & Valuation Team

Forensic & Valuation team

Mary O'Connor


Mary is the Partner of the forensic & valuation service area and has worked exclusively in the field of valuation and financial forensics since 1979. She specializes in business valuation and the appraisal of tangible and intangible assets for litigation with special focus in health care, intangible assets in property tax appeal, securities, subrogation and insurance matters. Mary has provided litigation consulting and expert witness testimony to federal, state and local jurisdictions (including U.S. Tax Court, Delaware Chancery and Property Tax Appeals Boards) nationally and internationally.

Brian McCabe


Brian J. McCabe, ASA, has worked exclusively in the field of valuation since 2002. He has extensive experience preparing valuations for gift and estate purposes, litigation support, S Corp Conversion, employee stock ownership plans (ESOPs), and management planning purposes. Brian has performed appraisals of privately-held operating companies, family limited partnerships (FLPs), fractional interests in real estate, debt securities, preferred stock, and restricted stock.

Jim Sullivan


James M. Sullivan, JD, CFE, CIG, is a managing director in Sikich’s dispute advisory service area. In this role, Jim conducts investigations of alleged fraud, evaluates systems and procedures for control weaknesses, and recommends appropriate controls to prevent fraud. He served for 12 years as the Inspector General for the Chicago Board of Education, the third-largest public education system in the country. During his tenure, Jim’s office investigated and exposed multi-million dollar fraud schemes committed by vendors resulting in criminal convictions and the civil recovery of funds from the unscrupulous contractors.

David Wharton

David Wharton, CPA, CFE, CFF
Senior Manager

David Wharton, CPA, CFE, CFF, is a senior manager for dispute advisory services. He has over 13 years of experience providing forensic accounting, dispute advisory and financial consulting services to the business and legal community. David’s experience covers a wide array of complex matters including: commercial litigation, determination of lost profits, class actions, intellectual property disputes, corporate financial fraud investigations, whistleblower investigations, and insurance claims investigations like business interruption and fidelity bond claims.