William Frentzen

Partner | San Francisco

wfrentzen@mofo.com | (415) 268-6413 wfrentzen@mofo.com
(415) 268-6413

William Frentzen is a partner in Morrison & Foerster’s Securities Litigation, Enforcement, and White Collar Defense group and is the former chief of the Corporate and Securities Fraud Unit for the U.S. Attorney’s Office for the Northern District of California (NDCA). He represents companies and their executives in internal and government investigations, white-collar criminal defense matters, and parallel civil litigation related to allegations of corporate fraud, securities fraud, public corruption, intellectual property crimes, crisis response related to cyber breaches, money laundering, healthcare fraud, digital currency crimes, tax crimes, cybercrime, and Racketeer Influenced and Corrupt Organization (RICO) Act violations, among others. William also has significant experience in cross-border matters, having led a variety of prosecutions with extradition and Mutual Legal Assistance Treaty (MLAT) elements and joint investigations with non-U.S. government authorities. He also serves as an advisor for Haun Ventures, an investment firm focused on web3 ventures, tokens, and projects related to blockchain technology, digital currency, and crypto assets.

Before joining MoFo, William spent over 20 years at the U.S. Department of Justice (DOJ) where he most recently served as chief of the Corporate and Securities Fraud Unit for NDCA. Prior to that he also served as chief of the Corporate Fraud Strike Force, as Senior Trial Counsel, and as chief of the Organized Crime Strike Force for that office, and he also developed the country’s first Cryptocurrency Crime Coordinator position within a U.S. Attorney’s Office. William has also served as an Assistant United States Attorney (AUSA) in the U.S. Attorney’s Offices for the District of Columbia and the Southern District of Georgia and as Associate Independent Counsel in the Office of Independent Counsel.

Over the course of his career, William has successfully investigated and tried over 40 federal felony jury trials around the country, which encompassed some of the longest and most complex criminal cases in the NDCA. His trial capabilities were recognized through his appointment as Senior Trial Counsel for the NDCA, which was a position created in acknowledgement of William’s unique ability to try cases within the NDCA. William’s trial experience includes securing the conviction of a chief financial officer related to accounting and securities fraud charges arising out of the $11 billion dollar sale of a software company, which became the largest fraud case in the history of the NDCA. He has also achieved several high-profile criminal resolutions, including the first ever criminal prosecution for violating the Lobbying Disclosure Act against an infamous lobbyist and the conviction of two corrupt federal agents for stealing and extorting digital currency during their investigation of the Silk Road dark website.

Throughout his time as a prosecutor, William has coordinated with a variety of state, local, and federal law enforcement partners including the U.S. Securities Exchange Commission (SEC), Federal Bureau of Investigation (FBI), Internal Revenue System (IRS), Commodity Futures Trading Commission (CFTC), Federal Trade Commission (FTC), Office of Foreign Assets Control (OFAC), and Financial Crimes Enforcement Network (FinCEN), among others. He has also worked with numerous global law enforcement agencies, including INTERPOL, Europol, the UK Serious Fraud Office, and the UK National Crime Agency, among others.

William received his J.D., cum laude, from Tulane Law School and his B.A. from New College of the University of South Florida.

Representative Experience

  • Accounting and securities fraud charges against a chief executive officer, chief financial officer, and founder arising out of the $11 billion dollar sale of a software company, which led to the conviction of the chief financial officer and became the largest fraud case in the history of NDCA.
  • Money laundering, conspiracy to commit international money laundering, and operating an unlicensed money exchange charges against an unregistered digital currency exchange and its primary operator.
  • Seizure of billions of dollars in digital currency, which is one of the largest seizures in U.S. history, related to the Silk Road digital black-market platform.
  • Money laundering, computer intrusion, and conspiracy to commit wire fraud charges against the perpetrators of a major cyber breach involving VIP customer accounts of a large social networking service and cryptocurrency fraud. This was one of the fastest investigated and charged cyber incidents of recent times.
  • Securities fraud charges against an online cryptocurrency investment manager and its principal related to a fraudulent investment scheme valued at US $20 million.
  • Theft of trade secrets charges against the chief engineer of a multinational transportation company regarding the misappropriation of self-driving vehicle technology.
  • Public corruption charges against the heads of various municipal and public utilities operations in California.
  • Bribery and honest services charges against a California State Senator.
  • Violation of the Anti-Kickback Statute charges against over 30 doctors, healthcare professionals, and a large home health provider related to illicit patient referrals.
  • Securities and healthcare fraud charges against the founder and president of a medical testing start-up related to fake COVID testing, which was the first case in which securities fraud charges were brought in the context of COVID.
  • Novel Lobbying Disclosure Act violations and fraud charges related to a multimillion-dollar Initial Coin Offering against a prominent lobbyist.
  • Obstruction of justice charges again the chief security officer of a multinational transportation company regarding a significant data breach.
  • Bid-rigging, bribery, obstruction of justice, and wire fraud charges resulting in trial against a San Francisco politician, political consultants, and developers related to federal and state government contracts.
  • RICO Act charges and trials against dozens of notorious international organized crime syndicates.
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