Thomas Drake still thinks about waking up a free man, instead of the lifelong prison term he was promised by the government he used to work for.

Drake woke up Wednesday in a guesthouse on the campus of Gustavus Adolphus College in St. Peter, Minn. The former senior executive of the National Security Agency spoke at the college's annual Mayday Peace Conference last week as part of his second career: the whistleblower warning the nation about the rise of mass surveillance.

After a career in the Air Force and stints as a CIA analyst and an intelligence agency contractor, Drake took a job at the NSA, perhaps the country's most secretive federal agency, which exists to protect the nation by intercepting and analyzing telephone and digital communications. His first day of work was Sept. 11, 2001.

Within months, he said, he was disturbed by what he saw. To stop future attacks, the NSA was collecting huge volumes of communications of Americans, flouting the Constitution's protection against warrantless searches, he said.

He said he raised his concerns internally at first, to no effect. In 2006, he contacted a reporter at the Baltimore Sun, which then published a series of stories about Trailblazer, an NSA program it described as violating privacy at huge cost and dubious benefit.

Drake said he chose defending the law over loyalty to the agency. "If that meant going to prison, then I would go to prison. I knew that in blowing the whistle, shortly after 9/11, I would expose myself to that possibility, and not just lose my job, but lose everything."

In 2007, FBI agents raided his home in Maryland. Drake was left in limbo for two years, wondering whether the new Obama administration would continue the case. He got his answer in April 2010 when he was charged with 10 felony counts. Five of them invoked the Espionage Act, a law that's intended for saboteurs, not whistleblowers.

Four days before his trial was to begin in 2011, the government dropped the espionage charges and allowed Drake to plead guilty to a misdemeanor of misusing a government computer. He was sentenced to community service, probation and a $25 court fee.

The judge lashed out at the prosecution for putting Drake through "four years of hell."

By then, Drake could no longer afford private attorneys and had found a job at an Apple Store, where he still works today. Yet he had the unique distinction of having beaten the rap in the Obama administration's unprecedented use of the Espionage Act to punish leakers.

Now he's a celebrity in the small society of federal whistleblowers, a subject of documentary films and profiles, with his own book on the way and plans to teach.

"We are in serious distress as a nation and as a society," he told the conference. "What would you sacrifice in defending the Constitution? What would you be willing to give up for liberty and freedom?"

Drake and other NSA whistleblowers were vindicated when NSA contractor Edward Snowden went public in 2013 with secret records that showed the enormous scale of illegal spying by the agency. Snowden, in exile in Russia, has also been charged under the Espionage Act.

In October 2013, Drake was one of four Americans, including former Minneapolis FBI special agent Coleen Rowley, who traveled to Moscow to deliver an award to Snowden. Rowley shared the stage with Drake at Gustavus last week.

"I'm a living example of how it's possible to speak truth to power," Drake said.

Asked last week for a statement about Drake, the National Security Agency responded: "We have nothing for you on this request."

Contact James Eli Shiffer at james.shiffer@startribune.com or 612-673-4116.