FBI agent-turned-traitor Robert Hanssen, who spied for the old Soviet Union and later the Russians, died Monday in the cell where he was serving 15 consecutive life sentences for betraying his country, federal prison officials said.
Hanssen, 79, was "found unresponsive" around 6:55 a.m. at the federal supermax prison in Florence, Colorado, the Bureau of Prisons said in a statement.
Despite attempts to revive him, Hanssen was pronounced dead by the EMS workers who had tried to save him, the BOP said.
The FBI was notified but the BOP did not indicate whether Hanssen's death was under investigation.
Hanssen began spying for the Soviets in 1979, three years after he joined the FBI, while assigned to a counterintelligence unit in New York City.
Using the alias "Ramon Garcia," the Chicago-born Hanssen sold "highly-classified national security information" to Moscow for $1.4 million in cash, bank funds and diamonds, the FBI says on its official history page.
Hanssen's career as a Soviet spy was interrupted in 1980, when he was caught by his wife Bonnie with top secret documents.
"He told me he was just tricking the Russians and feeding them false information," she later told The New York Times. "He never said he was spying. I told him I thought it was insane."
Hanssen’s wife forced him to confess to a priest with ties to Opus Dei, the ultra-conservative Catholic organization to which the couple belonged. The priest said he wouldn’t go to the authorities if Hanssen vowed to stop what he was doing and gave the money to charity.
But by 1985, Hanssen was once again selling American secrets to Moscow, the FBI said.
Hanssen was arrested in 2001 after making a dead drop of classified material wrapped in a plastic bag at a Virginia park near his home while under surveillance by the FBI, which had been watching him for months.
Caught red-handed, Hanssen pleaded guilty to selling thousands of classified documents over the years detailing U.S. strategies for nuclear war as well as counterintelligence information.
Hanssen also revealed to his Moscow spymasters the existence of an underground secret eavesdropping tunnel built by the FBI under the Soviet Embassy.
At the time, the Justice Department described the situation as “possibly the worst intelligence disaster in US history.”
Hanssen, at his sentencing, said he was sorry and admitted he did it for the money.
"I apologize for my behavior. I am shamed by it,” Hanssen, a married father of six, told the judge. “I have opened the door for calumny against my totally innocent wife and children. I have hurt so many deeply.”
Since July 17, 2002, Hanssen was a prisoner at the Florence maximum-security prison, the most secure federal prison in the country — and home to other high-profile inmates like Al Qaeda terrorist Zacarias Moussaoui, Boston Marathon bomber Dzhokhar Tsarnaev, failed “shoe bomber” Richard Reid, and "Unabomber" Ted Kaczynski.
Hanssen's story became the basis for the 2007 spy thriller "Breach," which starred Chris Cooper as the disgraced G-man.
Billy Ray, who directed and co-wrote the movie, said Hanssen's actions "made us a fundamentally weaker country."
"When you think about what he did and the level of contempt that was required to do it, as well as the number of people who died as a direct result of his actions, it’s pretty shocking," Ray told NBC News. "I don’t know if there’s an equivalent in American history.”