- A few months later, in part thanks to Mr Garcia's covert work, the whole country would as well.
- Hanssen's arrest in February 2001 sent shockwaves through the intelligence community and the extent of his double life burst on to the front pages.
Robert Hanssen was one of the most damaging spies in the history of the FBI. The former US agent, who has died in prison, leaked top secrets to Moscow for nearly 20 years - betrayals that the agency says cost lives. It took 300 agents to finally bring him down. Two of them who played a central part tell us how they did it.
In December 2000, FBI agent Richard Garcia had a curious visit from a colleague overseeing the Russia desk.
"He asked, 'Do you know a guy named Robert Hanssen?'" Mr Garcia recalled. "I said, 'No'."
The official responded: "Good. Because you're about to."
A few months later, in part thanks to Mr Garcia's covert work, the whole country would as well.
Hanssen's arrest in February 2001 sent shockwaves through the intelligence community and the extent of his double life burst on to the front pages.
More than two decades later, on Monday this week, authorities announced that he had been found unresponsive in his cell at the maximum-security prison in Colorado where he was serving a life sentence. He was 79 and is thought to have died from natural causes.
Mr Garcia, now 70 and retired from the FBI, reacted tersely to the news. "Good riddance," he said.
Deadly acts of betrayal
Hanssen had studied Russian in college and began working for the FBI in 1976. Within a decade, he was double-crossing the bureau. Starting in 1985, Hanssen operated as a destructive mole within the US government, selling top secret documents to the USSR and Russia, and compromising the identities of undercover spies.
According to the 100-page affidavit outlining his crimes, Hanssen's espionage resulted in the arrest and imprisonment of three US sources and the execution of two more.
Some of the top-secret documents that Hanssen handed over included a US intelligence assessment of Soviet attempts to gather intelligence on American nuclear programmes. Hanssen gave information to the KGB, and later its post-Soviet iteration, the SVR.
In exchange for his deceptions, the Russians paid Hanssen $1.4m - $600,000 in cash and diamonds, and another $800,000 placed in a bank account.
Hanssen operated under the radar for so long due to his old-school espionage methods. He relied on "dead drops", a method of physically leaving materials for his handlers to discover. He chose mundane sites throughout the suburban Virginia neighbourhoods that surround Washington to deliver the stolen intelligence.
His handlers in Moscow did not know his identity. He went by the alias "Ramon Garcia", of no relation to Robert Garcia who mused the coincidence might have irked Hanssen once they met.
His activities continued long after the Berlin Wall fell and the USSR disintegrated. He was attempting to communicate with the Russians right up until the moment of his arrest.
But a series of intelligence breakthroughs eventually put the FBI and the US intelligence apparatus onto his tail.
Identifying the mole
US intelligence officials had suspected a spy in their midst since the 1990s, but it took a few years to zero in on Hanssen.
Then a Russian asset working for the US obtained the Russian dossier on their man in Virginia. Inside US intelligence officials discovered a recording of a phone call Hanssen made to his handlers, as well as fingerprints left on trash bags used for dead drops.
By November 2000, they had their man. But now they had to prove it.
The FBI hatched a plan to place Hanssen under surveillance by transferring him out of the State Department where he worked and creating a bogus job at the Bureau where operatives could monitor him.