Spencer Fane LLP Logo

Mark A. Thornhill


Spencer Fane attorney Mark A. Thornill square

T 816.292.8119
F 816.474.3216

Mark Thornhill represents individuals and organizations in white collar criminal and regulatory cases. His white collar work started as a prosecutor with the United States Department of Justice – Criminal Tax Section. At Spencer Fane, Mark defends the full array of white-collar cases – anti-trust, bank fraud, computer fraud, environmental, health care, mail fraud/wire fraud, and tax evasion. In regulatory cases, Mark represents individuals and companies before the Securities and Exchange Commission, the Financial Institutions Regulatory Authority (FINRA), and the Environmental Protection Agency, among others.

Mark also conducts internal investigations. In an investigation for a large mid-west bank, Mark uncovered more than $1 million in fraudulent transactions by the bank president. Mark’s investigation for an IT company revealed more than $200,000 in unauthorized payments to the CEO. Mark investigated allegations of corruption in connection with medical research grants and in connection with the pricing of securities. Mark recently worked with the National Institute for Trial Advocacy to develop an internal investigation instructional program.

Mark’s civil trial focus is on fiduciary duty cases. He has defended domestic and foreign companies or their directors in fiduciary duty trials in courts in the mid-west and in Delaware. These cases have included issues of cash-out mergers, customary practices in Europe, aiding and abetting, loyalty disputes and a broad range of evaluation techniques, among other issues. Mark also represents a national life and disability insurance company against lawsuits in mid-west states.


  • Representation of manufacturing company in federal criminal prosecution resulting from a chemical release.
  • Representation of employees in federal criminal investigation of alleged false claims.
  • Representation of employees in company’s internal investigation of possible improper payments.
  • Representation of employees in federal criminal investigations of accidents at chemical manufacturing facilities.
  • Representation of companies that were victims of embezzlement.
  • Dismissal of fiduciary duty and fraud claims in securities case in Delaware.
  • Defense verdict in the Delaware Court of Chancery and on appeal for a Swiss company against claims of fiduciary breach and unlawful interference.
  • Defense of a Native-American corporation in an investigation of federal criminal laws related to taxation.
  • Defense of patent infringement claims tried before the International Trade Commission.


  • 2021 Diastole Scholar’s Center: Vice Chair of the Board
  • 2019 Diastole Scholar’s Center: Strategic Planning Committee
  • 2017 University of Missouri – Kansas City: Cockefair Chair Advisory Committee
  • 2017 Legal Aid of Western Missouri: Co-Chair, Justice for All Campaign
  • 2016-17 Planned Parenthood of the Great Plains: Board of Directors Vice-Chair
  • 2004-05 Truman Medical Center (Kansas City’s academic hospital): Board of Directors Chair
  • 1996-98 AIDS Service Foundation: Board of Directors
  • 1996 Kansas City Free Health Clinic (Now Kansas City Care Clinic): Board of Directors Chair


  • Selected to The Best Lawyers in America,® since 2008 for White Collar Practice
  • Selected as Best White Collar Lawyer in Western Missouri in 2014
  • Selected to Missouri & Kansas Super Lawyers® for Commercial Litigation Practice since 2008

Contact Mark Thornhill at 816.292.8119 or mthornhill@spencerfane.com.