Mark Lee Klein (May 2, 1945 – March 8, 2025) was an American

AT&T AT&T Inc., an abbreviation for its predecessor's former name, the American Telephone and Telegraph Company, is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the w ...

technician and

whistleblower Whistleblowing (also whistle-blowing or whistle blowing) is the activity of a person, often an employee, revealing information about activity within a private or public organization that is deemed illegal, immoral, illicit, unsafe, unethical or ...

who revealed details of the company's cooperation with the United States

National Security Agency The National Security Agency (NSA) is an intelligence agency of the United States Department of Defense, under the authority of the director of national intelligence (DNI). The NSA is responsible for global monitoring, collection, and proces ...

in installing network hardware at a site known as Room 641A to monitor, capture and process American

telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

. The subsequent media coverage became a major story in May 2006.

Early life and education

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 Cornell University is a Private university, private Ivy League research university based in Ithaca, New York, United States. The university was co-founded by American philanthropist Ezra Cornell and historian and educator Andrew Dickson W ...

with a bachelor's degree in history in 1966. He later attended technical school and worked in computer manufacturing before working at AT&T.

Career

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. Starting in October 2003, he returned to the role of Communications Technician, after which he retired in May 2004.

Whistleblowing

In early 2006, Klein revealed details about AT&T secretive cooperation with the National Security Agency's mass surveillance program. He found that the NSA was using a splitter to intercept and monitor all internet and other data traffic, which was then directed to a secure room at AT&T’s facility, called Room 641A. He came across blueprints and documents outlining the technology, the program’s existence, and AT&T's involvement with the NSA. He also found evidence that the program was active in other cities across the United States. This surveillance initiative followed the Patriot Act, which granted American defense and intelligence agencies broader powers after the 9/11 attacks. The

Electronic Frontier Foundation The Electronic Frontier Foundation (EFF) is an American international non-profit digital rights group based in San Francisco, California. It was founded in 1990 to promote Internet civil liberties. It provides funds for legal defense in court, ...

(EFF) filed a lawsuit shortly afterwards. In 2009, Klein wrote a book titled ''Wiring Up The Big Brother Machine...And Fighting It'', in which he wrote about his experience discovering the relationship and his efforts to tell the public.

Personal life and death

Klein was predeceased by his wife Linda Thurston. Klein died from

pancreatic cancer Pancreatic cancer arises when cell (biology), cells in the pancreas, a glandular organ behind the stomach, begin to multiply out of control and form a Neoplasm, mass. These cancerous cells have the malignant, ability to invade other parts of ...

in Oakland on March 8, 2025, at the age of 79.

Awards

In recognition of his actions, the EFF picked Klein as one of the winners of its 2008 Pioneer Awards.

References

External links

Klein's Declaration (unredacted)
from the case '' Hepting v. AT&T'' –

ABC ''Nightline'' Interview with Klein
*
''Wired'' coverage

Spying On The Home Front, ''Frontline'', PBS
*

* ttps://www.eff.org/deeplinks/2008/12/first-interview-nsa-whistleblower First Interview with the NSA Whistleblowerat EFF
''Wiring Up the Big Brother Machine ...And Fighting It'' by Mark Klein

''Wired'' (2008) interview with Klein
{{DEFAULTSORT:Klein, Mark 1945 births 2025 deaths American whistleblowers National Security Agency American computer specialists AT&T people Deaths from pancreatic cancer People from New York City