<ul><li>Mark Klein, a former AT&T technician turned whistleblower, has died at age 79.</li><li>Klein exposed the secret NSA surveillance by revealing the use of a secret room in an AT&T hub in San Francisco in 2006.</li><li>His disclosure confirmed the U.S. government's access to internet data on millions of Americans.</li><li>The death of Mark Klein was confirmed by the Electronic Frontier Foundation, a digital rights group.</li></ul>

AT&T technician Mark Klein, who exposed secret NSA spying, dies

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