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Mark J. Lesko is a former federal prosecutor and experienced trial lawyer who spent years directing complex legal teams and leading large institutions in the public and private sectors. Mark has personally tried more than three dozen cases, handled 25 appeals and 15 appellate oral arguments, and conducted and supervised thousands of investigations, prosecutions, and cases across criminal, civil, and regulatory practices.

Mark recently served as Acting Assistant Attorney General (AAG) for DOJ’s National Security Division. In this role, he was the DOJ’s highest-ranking national security lawyer and held one of the highest security clearances in the U.S. government. Mark oversaw nearly 400 employees who protect the nation’s security against terrorism, espionage, cybersecurity threats, and other national security threats. During his time as Acting AAG, Mark frequently briefed various congressional committees and the White House on highly sensitive matters. He led the DOJ’s counterterrorism efforts, including a particular focus on combatting cyber-based terrorism threats, and oversaw the Export Control Section, which investigates and prosecutes espionage cases, including cases involving economic espionage, theft of trade secrets, the illegal export of military and strategic commodities, and certain cyber-related activity. He also led the DOJ’s work on the Committee on Foreign Investment in the United States (CFIUS), supervised cases involving the unauthorized disclosure of classified information and the enforcement of the Foreign Agents Registration Act (FARA), and led the implementation of reforms related to surveillance authorizations under the Foreign Intelligence Surveillance Act (FISA).

Prior to this, Mark served as Acting United States Attorney for the Eastern District of New York (EDNY), where he supervised more than 175 AUSAs and was responsible for all criminal prosecutions and civil litigation on behalf of the district. Mark was a federal prosecutor for over 13 years and he held a number of other leadership positions in the EDNY, including First Assistant United States Attorney, Special Counsel to the U.S. Attorney, and Deputy Chief of the Long Island Criminal Division. Mark received the Attorney General’s Award for Distinguished Service in connection with the prosecution and trial conviction of NXIVM cult leader Keith Raniere. Mark was also an AUSA in the District of Columbia, where he served in the homicide/major crimes section.  

Mark was also the three-time elected Supervisor of the Town of Brookhaven – New York’s second-largest Town with approximately 486,000 residents – where he supervised approximately 2,000 employees and managed a $270 million budget.

Mark also previously served as Vice President for Economic Development at Hofstra University and as Executive Director of Accelerate Long Island, where he ran a regional investment fund that invested in startup technology companies. In addition, Mark was a commercial litigator at large law firms in Washington, D.C. and Pittsburgh, Pennsylvania. Mark practices out of Greenberg Traurig’s Long Island, New York City, and Washington, D.C. offices.



  • Member of the trial team in U.S. v. Raniere, an eight-week complex racketeering trial where the defendant, the leader of the NXIVM self-help group, was convicted of racketeering, sex trafficking, and other related offenses. The defendant was sentenced to 120 years’ imprisonment.°
  • U.S. v. Joaquin “El Chapo” Guzman Loera (supervised case resulting in conviction of leader of the Sinaloa cartel at trial).°
  • Supervised and participated in the prosecution of a major multinational technology company and its CFO.°
  • Supervised a case involving a $6 billion 1MDB Malaysian bond fraud.°
  • Supervised a $2.9 billion FCPA resolution involving a major financial institution, including its subsidiary’s guilty plea. °
  • Lead prosecutor in U.S. v. Sabhnani, known as the “Muttontown Slave Case,” where the defendants were convicted of detaining two domestic servants in a state of servitude after a ten-week trial.°

°The above representations were handled by Mr. Lesko prior to his joining Greenberg Traurig, LLP.

  • Acting Assistant Attorney General, United States Department of Justice, National Security Division, 2021
  • United States Attorney’s Office for the Eastern District of New York, 2002-2009, 2018-2021
    • Acting United States Attorney, 2021
    • First Assistant United States Attorney, 2019-2021
    • Special Counsel to the United States Attorney, 2018-2019
    • Assistant United States Attorney, 2018-2022
    • Deputy Chief, Long Island Criminal Division, 2005-2009
    • Assistant United States Attorney, 2002-2009
  • Supervisor, Town of Brookhaven, 2009-2012
  • Assistant United States Attorney, United States Attorney’s Office for the District of Columbia, 1999-2002
  • Hofstra University, Hempstead, NY
    • Vice President for Economic Development, 2016-2018
    • Executive Dean, Hofstra University’s Center for Entrepreneurship, 2015-2018
    • Adjunct Professor of Law, Maurice A. Deane School of Law, 2016-2018
    • Adjunct Professor, Frank G. Zarb School of Business, 2018
    • Executive Dean, Scott Skodnek Business Development Center, 2016-2018
    • Executive Dean, Wilbur F. Breslin Center for Real Estate Studies, 2016-2018
  • Accelerate Long Island, Melville NY
    • Executive Director, 2012-2016

Recognition & Leadership

  • Listed, The Legal 500 United States, Dispute Resolution> Corporate Investigations and White-Collar Criminal Defense, 2023
  • Listed, City & State New York, "Long Island Power 100," 2022-2023
  • Recipient, U.S. Attorney's Office for the Eastern District of New York, "The Attorney General’s Award for Distinguished Service," 2022
  • Honoree, Frank G. Zarb School of Business’s Beta Gamma Sigma Chapter, 2017
  • Listed, Long Island Press, “Power List,” 2012
  • Honoree, Long Island Business Development Council, “Visionary of the Year,” 2011
  • Named, Long Island Business News, One of Long Island’s “Top 20 Influentials,” 2011
  • Honoree, Times Beacon Record Newspapers, “Man of the Year in Government,” 2010, 2011
  • Member, Board of Directors, Accelerate Long Island, 2013-2018
  • Co-Chair, Investment Review Committee, Accelerate New York Seed Fund, 2017-2018
  • Member, Executive Committee, Long Island Real Estate Group, 2016-2018
  • Member, Advisory Board, Clean Energy Business Incubator Program, 2015-2018
  • Member, Central Pine Barrens Joint Planning & Policy Commission, 2009-2012
  • Chair, Suffolk County Supervisors’ Association, 2011-2012
  • Member, Long Island’s Regional Economic Development Council, 2011-2012


  • J.D., Georgetown University Law Center, 1994
    • Notes Editor, Georgetown Immigration Law Journal
  • B.A., Yale University, 1989
  • District of Columbia
  • New York
  • U.S. District Court for the Eastern District of New York
  • U.S. District Court for the Southern District of New York
  • U.S. District Court for the Western District of Pennsylvania
  • U.S. Court of Appeals for the Second Circuit