John's practice focuses on government and internal investigations, white collar defense, complex civil litigation, and regulatory compliance. A “seasoned trial lawyer” (Businessweek, July 2013) who has tried 15 federal criminal cases, John has an effective courtroom style that is known to “win over jurors” (Forbes, December 2014). He also has briefed or argued over 15 federal appeals.

From 2006 until 2015, John served as an Assistant U.S. Attorney in the Southern District of New York, one of the premier prosecuting offices in the world, and was known as one of its most experienced trial lawyers. At the U.S. Attorney’s Office, he was a senior member of the Securities and Commodities Fraud Task Force, where he prosecuted and tried some of the government’s most significant cases. In addition, he also conducted numerous investigations with law enforcement agencies and regulators such as the Securities and Exchange Commission, the Commodity Futures Trading Commission, the Federal Bureau of Investigation, the Internal Revenue Service, and the Department of Labor, and coordinated investigations with a number of international law enforcement agencies. 

John has extensive experience in securities and commodities fraud, accounting fraud, tax fraud, and anti-money laundering matters.

From 2001 until 2006, John was an associate at Cravath, Swaine & Moore, where he worked on a variety of securities fraud, antitrust and bankruptcy adversary proceeding matters. Prior to becoming a lawyer, he volunteered with Americorps and taught high school equivalency and job training to troubled teenagers.

John has prosecuted many important cases, including: 

  • The investigation and prosecution of the hedge fund S.A.C. Capital Advisors, which led to a guilty plea by the fund and the imposition of $1.8 billion in criminal and civil penalties. John was awarded the Executive Office of U.S. Attorneys’ Director’s Award for Superior Performance for his work on the matter
  • The six-month trial of five former employees of Bernard L. Madoff Investment Securities in which Mr. Zach’s direct examination of the principle cooperating witness “took the jurors on a vivid and intricate journey through virtually the entire life of Madoff Securities” and in which his cross-examination of a defendant provided “the trial’s Perry Mason moment” (Forbes, December 2014).  He was awarded the Department of Justice’s John Marshall Award for his work on the case
  • The trial of two former hedge fund managers on insider trading charges based on the passing of material nonpublic information acquired by a group of analysts working at different investment firms
  • The extradition and prosecution of Christopher Coke, who The Economist called “Jamaica’s most prominent mobster” and whose “gang operated a virtual para-state” and “vigilante justice system” within the country. In addition, handled various money-laundering, corruption and racketeering matters involving the Dominican Republic and other Caribbean countries.

A New Federal Theory of Corruption? New York Law Journal, December 11, 2017

  • University of Texas at Austin School of Law, J.D., with honors; Member, Texas Law Review
  • University of Notre Dame, B.A., English and Philosophy


  • New York

Lawdragon’s 500 Leading Plaintiff Financial Lawyers (2023)

Litigator of the WeekThe American Lawyer (2022)

Assistant U.S. Attorney, Southern District of New York