Mark Klein is a former AT&T technician who leaked knowledge of his company's cooperation with the United States National Security Agency in installing network hardware to monitor, capture and process American telecommunications. The subsequent media coverage became a major story in May 2006.
For over 22 years Mark Klein worked for AT&T. Starting with the company as a Communications Technician in New York, where he remained from November 1981 until March 1991, he later continued in that capacity in California until 1998. From January 1998 to October 2003, Klein worked as a Computer Network Associate in San Francisco. From October 2003 to May 2004 he returned to the role of Communications Technician, after which he retired in May 2004.
- Klein's Declaration (unredacted), from the case Hepting v. AT&T]] - Electronic Frontier Foundation
- ABC Nightline Interview with Klein
- Klein's memo about the NSA program
- Wired coverage
- PBS NOW | Whistleblower Mark Klein
- PBS NOW | For Your Eyes Only?
- Spying On The Home Front, Frontline, PBS
- A Story of Surveillance, Washington Post, November 7, 2007
- First Interview with the NSA Whistleblower at EFF
- Wiring Up the Big Brother Machine ...And Fighting It by Mark Klein
- Wired (2008) interview with Klein