Mark Klein

MARK KLEIN is the whistleblower who exposed AT&T's participation in the National Security Agency's illegal warrantless spying on millions of Americans.

Klein grew up in New York City and in 1962 entered Cornell University's School of Engineering. As the 1960s exploded in social upheaval he was moved with his generation to investigate society and graduated in 1966 with a B.A. in history. Later he returned to technical school, obtaining certificates in electronics and computers which led to employment in computer manufacturing in the 1970s.

He was hired by AT&T in 1981 as a communications technician and worked for the company for over 22 years. In 2003 he discovered the illicit National Security Agency (NSA) installation in San Francisco and in 2006 he tried to bring it to public attention, becoming a witness for a lawsuit against AT&T brought by the Electronic Frontier Foundation. Retired since 2004, Klein now lives in the San Francisco Bay Area with his wife.