Mark Klein

Mark Lee Klein (May 2, 1945 – March 8, 2025) was an American AT&T technician and whistleblower who revealed details of the company's cooperation with the United States National Security Agency in installing network hardware at a site known as Room 641A to monitor, capture and process American telecommunications. The subsequent media coverage became a major story in May 2006.

Klein was born the younger of two children in Brooklyn on May 2, 1945. His mother was a school teacher and his father was a pharmaceutical executive. Klein graduated from Cornell University with a bachelor's degree in… More on Wikipedia →