Mark Klein, AT&T Whistleblower Who Exposed NSA’s Mass Surveillance, Dies

Published on March 13, 2025
Mark Klein in the 2007 PBS Frontline episode "Spying on the Home Front" (left) and door revealed to be an NSA spying room at AT&T in the mid-2000s.

Before Edward Snowden, Mark Klein blew the whistle on NSA internet spying.