Eric O'Neill

O'Neill's memoir about the Hanssen case, Gray Day: My Undercover Mission to Expose America's First Cyber Spy, was published by Penguin Random House in spring 2019.

On March 16, 2016, O'Neill was named National Security Strategist for Carbon Black, an endpoint security company.

In July 2013, O'Neill co-founded the Schiltron Group, a supply chain assurance and critical infrastructure protection company.

In February 2009, O'Neill co-founded The Georgetown Group, an investigative and risk management company.

O'Neill is portrayed by Ryan Phillippe in the 2007 thriller Breach, which depicts O'Neill's role in the investigation and capture of Hanssen. A feature-length commentary track on the DVD features O'Neill with director Billy Ray. O'Neill expands on the film, offering additional background and details, as well as noting where actual events were changed on the film for dramatic purposes.

Following the Hanssen case, O'Neill decided to leave the FBI in order to focus on law school. O'Neill earned a J.D. with honors from The George Washington University Law School in 2003. He has been admitted to the bar in Maryland and in the District of Columbia. After graduating from law school, O'Neill joined DLA Piper US LLP as a Senior Associate in the Government Contracts Group. In December 2008, O'Neill left DLA Piper and accepted a position as General Counsel of Global Communities, formerly CHF International, a global humanitarian relief non-profit organization.

Hanssen was arrested on February 18, 2001, at Foxstone Park near his home in Vienna, Virginia, charged with selling American secrets to Russia for $1.4 million in cash and diamonds over a 22-year period. O'Neill's subterfuge had apparently deceived Hanssen, as part of the dead drop contained an evaluation of O'Neill's possibly replacing Hanssen as a mole when he retired. On 6 July 2001, Hanssen pleaded guilty to 15 counts of espionage. Hanssen was sentenced to life in prison. His treason has been described as "possibly the worst intelligence disaster in US history."

O'Neill graduated from Gonzaga College High School in Washington, D.C., in 1991. He earned a B.A., with honors, in political science and psychology from Auburn University in 1995, where he was a member of the Theta Xi fraternity.

Eric Michael O'Neill (born March 3, 1973) is an American former FBI counter-terrorism and counterintelligence operative. He worked as an Investigative Specialist with the Special Surveillance Group (SSG) and played a major role in the arrest, conviction, and imprisonment of FBI agent Robert Hanssen for spying on behalf of the Soviet Union and Russia. His book written about this experience, Gray Day: My Undercover Mission to Expose America's First Cyber Spy, was published in spring 2019. He is a public speaker and security expert who currently lectures internationally about espionage and national security, cybersecurity, fraud, corporate diligence and defense, hacking, and other topics.