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

Mark Klein, the former AT&T employee who helped expose the fact that the National Security Agency was spying on vast amounts of internet traffic in the U.S. during the mid-2000s, has died, according to the Electronic Frontier Foundation. Klein’s cause of death was not released.

Klein was an internet technician for AT&T in San Francisco and had recently retired when he read a New York Times article in late 2005 about mass surveillance of Americans being conducted by the NSA. The article didn’t contain much detail, and Klein went to the EFF in 2006 to help blow the whistle, explaining how NSA used a splitter for all internet traffic flowing through San Francisco, rerouting everything to a room at AT&T called 641A.

Klein told PBS Frontline in 2007 about the day in 2002 when the feds came in to build a new room at the AT&T building in San Francisco. The episode, “Spying on the Homefront,” detailed the ways that surveillance of Americans had ramped up in the wake of the 9/11 terror attacks. Legislation like The Patriot Act had expanded the government’s ability to spy on just about anyone at any time, but these new revelations about what George W. Bush’s administration was doing went above and beyond the law.

The PBS Frontline documentary in 2007 explained how Klein had discovered documents about the secret room 641A at AT&T and was particularly confused by a machine called the Narus STA 6400. Klein learned that the splitter system wasn’t just in San Francisco. They were established to monitor internet traffic in Seattle, San Jose, Los Angeles, and San Diego, along with presumably a host of other cities.

President Bush acknowledged the spying program in May 2006, invoking the terror attacks of 9/11 to justify the mass surveillance of internet and phone traffic. But he said it was all for public safety as he was pursuing the bad guys of Al Qaeda.

“After September the 11th, I vowed to the American people that our government would do everything within the law to protect them against another terrorist attack,” Bush said, according to a press release now housed at the National Archives.

“As part of this effort, I authorized the National Security Agency to intercept the international communications of people with known links to al Qaeda and related terrorist organizations,” the release continued. “In other words, if al Qaeda or their associates are making calls into the United States or out of the United States, we want to know what they’re saying.”

The NSA had not utilized the FISA courts to conduct its wiretapping, something that would’ve been next to impossible given the scope of what they wanted to achieve. And Bush even acknowledged this at the time, all while maintaining he was protecting civil liberties while keeping Americans safe from Al Qaeda.

Klein’s association with the EFF was vital for exposing what he knew. And the group is clearly grateful for him stepping forward. From the EFF obituary on Klein:

We used Mark’s evidence to bring two lawsuits against the NSA spying that he uncovered. The first was Hepting v. AT&T and the second was Jewel v. NSA. Mark also came with us to Washington D.C. to push for an end to the spying and demand accountability for it happening in secret for so many years. He wrote an account of his experience called Wiring Up the Big Brother Machine . . . And Fighting It.

Mark stood up and told the truth at great personal risk to himself and his family. AT&T threatened to sue him, although it wisely decided not to do so. While we were able to use his evidence to make some change, both EFF and Mark were ultimately let down by Congress and the Courts, which have refused to take the steps necessary to end the mass spying even after Edward Snowden provided even more evidence of it in 2013.

Klein will be remembered for helping reveal what his own government was doing, but it was interesting for anyone who lived through the Edward Snowden revelations to witness Klein’s actions already being ignored. Snowden leaked classified NSA documents in 2013, but very few articles mentioned Klein’s whistleblowing at the time.

NSA spying on vast quantities of internet traffic didn’t start with the mid-2000s. In fact, the U.S. intelligence agencies were there from the internet’s first baby steps. They helped invent the damn thing. NSA became a node on the ARPANET in the mid-1970s, just a few years after the network made its first host-to-host connection in 1969.

Surveillance of the internet by the U.S. government is obviously a huge issue that remains relevant today. And with President Donald Trump at the helm, there are very few guardrails to protect against the worst possible abuses. The problem is that even if another Klein were to pop up here in 2025 to tell the exact same story, it seems unlikely many people would even notice. Most Americans assume their activity online is being constantly monitored, if not by the government than by the Big Tech oligarchs who showed up in church with Trump on his inauguration day.

Sure, the government is probably monitoring your internet traffic. But does it even matter if the NSA is actually behind it, when Mark Zuckerberg is whispering all your secrets to the feds anyway?